Cumitech 32: Laboratory Diagnosis of Zoonotic Infections

MAY 1999

Laboratory Diagnosis Zoonotic Infections:

of

Viral, Rickettsial, and Parasitic Agents Obtained from Food Animals and Wildlife JAMES F. EVERMANN, LYNNE S. GARCIA, AND DIANA M. STONE COORDINATING

THOMAS

EDITOR

J. INZANA

umitech CUMULATIVE

TECHNIQUES

AND PROCEDURES

IN CLINICAL

MICROBIOLOGY

Cumitech 1B Cumitech 2B Cumitech 3A Cumitech 4A Cumitech SA Cumitech 6A Cumitech 7A Cumitech 8 Cumitech 9 Cumitech 10 Cumitech 11 Cumitech Cumitech Cumitech Cumitech Cumitech Cumitech Cumitech Cumitech Cumitech Cumitech Cumitech Cumitech Cumitech Cumitech Cumitech Cumitech

12A 13A 14A 15A 16A 17A 18A 19A 20 21 22 23 24 25 26 27

Cumitech 28 Cumitech 29 Cumitech 30 Cumitech Cumitech

31 32

Blood Cultures III l April 2 997 Laboratory Diagnosis of Urinary Tract Infections l November 1998 Quality Control and Quality Assurance Practices in Clinical Microbiology l May 3990 Laboratory Diagnosis of Gonorrhea l April 1993 Practical Anaerobic Bacteriology l December 1991 New Developments in Antimicrobial Agent Susceptibility Testing: a Practical Guide l February 1992 Laboratory Diagnosis of Lower Respiratory Tract Infections l September 1987 Detection of Microbial Antigens by Counterimmunoelectrophoresis l December 2 978 Collection and Processing of Bacteriological Specimens l August 1979 Laboratory Diagnosis of Upper Respiratory Tract Infections l December 1979 Practical Methods for Culture and Identification of Fungi in the Clinical Microbiology Laboratory l August 1980 Laboratory Diagnosis of Bacterial Diarrhea l April 1992 Laboratory Diagnosis of Ocular Infections l September 2 994 Laboratory Diagnosis of Central Nervous System Infections l March 3 993 Laboratory Diagnosis of Viral Infections l August 1994 Laboratory Diagnosis of the Mycobacterioses l October 1994 Laboratory Diagnosis of Female Genital Tract Infections *June 2 993 Laboratory Diagnosis of Hepatitis Viruses l November 1998 Laboratory Diagnosis of Chlamydia trachomatis Infections l January 2 999 Therapeutic Drug Monitoring: Antimicrobial Agents l October 2984 Laboratory Diagnosis of Viral Respiratory Disease l March 1986 Immunoserology of Staphylococcal Disease l August 1987 Infections of the Skin and Subcutaneous Tissues l June 1988 Rapid Detection of Viruses by Immunofluorescence l August 1988 Current Concepts and Approaches to Antimicrobial Agent Susceptibility Testing l December 1988 Laboratory Diagnosis of Viral Infections Producing Enteritis l September 2 989 Laboratory Diagnosis of Zoonotic Infections: Bacterial Infections Obtained from Companion and Laboratory Animals l February 1996 Laboratory Diagnosis of Zoonotic Infections: Chlamydial, Fungal, Viral, and Parasitic Infections Obtained from Companion and Laboratory Animals l February 1996 Laboratory Safety in Clinical Microbiology l July 2996 Selection and Use of Laboratory Procedures for Diagnosis of Parasitic Infections of the Gastrointestinal Tract l September 2 996 Verification and Validation of Procedures in the Clinical Microbiology Laboratory l February 1997 Laboratory Diagnosis of Zoonotic Infections: Viral, Rickettsial, and Parasitic Infections Obtained from Food Animals and Wildlife l Mny 2 999

Cum#echs should be cited as follows, e g Evermann, J F , L S Garcia, and D M Stone 1999 Cumitech 32, Laboratory dlagnosls of zoonotlc Infections viral, rlckettstal, and parasitic tnfectlons obtained from food animals and wIldlIfe Coordlnatlng ed , T J lnzana American Society for MIcrobIology, Washington, D C Editorial Jamlson,

Board for ASM Cumitechs: Frederick S Nolte, Charman, Vlckle Baselskl, Karen Knsher, Brenda McCurdy, Allan Truant, Allce S Welssfeld, Stephen

The purpose of the Cumltech series IS to provide consensus recommendations procedures for cllnlcal mIcrobIology laboratories which may lack the facllltles given are not proposed as “standard” methods Copyright 0 1999 American Society 1325 Massachusetts Avenue NW Washington, DC 20005-4171

for Microbiology

Lorraine Clarke, A Young

by the authors for fully evaluating

Curt A Gleaves,

Janet Handler, Richard

as to appropriate state-of-the-art operating routine or new methods The procedures

Laboratory Diagnosis of Zoonotic Infections: Viral, Rickettsial, and Parasitic Agents Obtained from Food Animals and Wildlife James F. Evermann College

of Veterinary

Medicine,

Washington

State University, Pullman, Washington 99164

Lynne S. Garcia University

of California

at Los Angeles

Medical

Center,

Los Angeles,

California 90095-I 713

Diana M. Stone College

of Veterinary

Medicine,

Washington

State University, Pullman, Washington 99164

COORDINATING EDITOR: Thomas J. Inzana Virginia-Maryland

Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061

Introduction . . . . . . . . . . . . . . . . . . . . . . .. . ..*............................................................. Viral and Rickettsial Infections . . ..*.................................................*........

1 2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..*.......*............*......... 2 Equine Morbillivirus Infections Hantavirus Infections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..*............*......*.........................* 4 Influenza ... ... ... ... ... ... ... ... ... ... .... .. .... ... ... ... ... ... .... ... ... ... ... ... ... ... ... .... .. .... ... ... ... .... ... ... ... 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..*.....................*.........*........... 7 Newcastle Disease Parapoxvirus Infections . . . . . . . . . . . . . . . . . . ..*................................*....*...........*........................ 8 Rabies . . . . . . . . . . . . . . . . . . . . . . . . ..*..................*.....................................*...............*.............*..*. 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..*..............*.....................*..*...... 12 Vesicular Stomatitis Filovirus Infections . . . . . . ..*...................................*...........................*....*..................... 13 Arenaviral Hemorrhagic Fevers ..*...........................*.......,........................................... 14 15 Q Fever ,....................................*............................................................................

Parasitic

Infections

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Introduction and Sample Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..**.....*.....*. Protozoa . . . ..*............................................................................*............................... *...*...................................*.....................................*......*........................ Nematodes Intestinal Cestodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..*...................*......... Trematodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..*.......*.....................................................

References

16 17 19 24 28

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . . 32

ing infectious diseases,many of which are zoonotic. New medical therapies that extend life in the elderly, genetic diseasesthat compromise normal immunity, treatments for neoplasia, and infectious diseasessuch as AIDS have also resulted in increased susceptibility of people to zoonotic agents that do not causeclinical symptoms in normal individuals. Zoonotic infections may be obtained directly from the animal or indirectly, such as through food or the

T

he close association and dependency people maintain with animals for food and companionship have always been a source of zoonotic infections. As the human population extends its boundaries into previously unpopulated forestland, it is exposed to agents that may be commensalsin their normal hosts but highly virulent in humans. Such exposures have sparked interest in the field of emerg1

2

Evermann

CUMITECH

et al.

environment contaminated with microorganisms from animals. Therefore, it is important for clinicians to be aware of the potential agents to which people, such as veterinarians and farmers, who maintain a close association with animals, who may have had only occasional exposure (e.g., wilderness campers), or who are immunocompromised may be exposed. It is also important for laboratory personnel to be aware of these potential zoonotic agents, particularly the less common agents, and the procedures used to diagnose them. Cumitechs 27 and 28 reviewed the ecology and diagnosis of zoonotic agents transmitted from companion and laboratory animals. This Cumitech will review the viral and parasitic zoonotic agents that can be obtained from food animals and wildlife. Coxiella burnetii, the bacterial agent of Q fever, will also be reviewed in this Cumitech because it is an obligate intracellular pathogen and is normally isolated in the virology laboratory. A later Cumitech will review the less common zoonotic bacterial and fungal agents that may be obtained from food animals and wildlife. In cases where a zoonotic agent can be obtained from a wide variety of animal species, the agent will be described in the Cumitech that reviews the more common or traditional hosts (e.g., Chlamydia psittaci was reviewed in Cumitech 28 and will not be described again here). Neither Cumitech at this time will review agents that are transmitted primarily by arthropods. Because the diagnosis of some zoonotic pathogens (particularly some viral agents) is beyond the scope of most hospital laboratories, referral laboratories are listed where appropriate. This Cumitech is not intended to be a procedure manual but rather highlights those agents that are considered zoonotic, how humans become infected with these agents, and the procedures used to diagnose and control these infections. VIRAL AND

RlCKEl-lWAL

INFECTIONS

Zoonotic infections from livestock and wildlife have been well recognized for a number of years (16,25). Although rabies has historically served as the prototype for zoonotic disease, it has become important to understand the wide scope that zoonotic infections encompass and the relatively new infections with which humans are confronted (62, 136). Within the past decade several new zoonotic viral agents, such as hantavirus and equine morbillivirus, have been described (25). What has become apparent is the need for epidemiologic investigations to understand the ecology (Table 1) of these agents in nature and for diagnosticians to understand how to handle the samples from diseased animals and humans in the safest manner possible (25, 72, 118, 136). Together with the newly described viruses men-

32

tioned above, there are examples of viral infections of livestock and wildlife that have been known for a number of years that pose occupational risk to humans working in close proximity to infectious secretions or excretions from the affected animals (71). Influenza virus has remarkable adaptability in nature because of its wide host range and segmented genome. Recent reports have indicated that transfection of avian influenza to a human h.as occurred, ending many years of specula tion that birds may serve as a direct source of influenza virus without an intermediate host, such as swine. Newcastle disease virus, parapoxvirus, vesicular stomatitis virus, the filoviruses, and C. burnetii are all considered zoonotic agents of humans in high-risk occupations. These include veterinarians, farmers, wildlife rehabilitation professionals, and humans engaged in processing meat animal by-products for human consumption (16,25, 136). Microbial agents capable of causing human infections will continue to persist in the environment. Viruses are dependent on a living reservoir and genomic flexibility to continue a pattern of persistence. It is important that microbiologists understand the ecology of infectious agents in nature and the artificial ecology of infections that are due to human intervention (136). A potential area requiring vigilance is the use of animal-derived tissues or by-products in humans such as through xenotransplantation (6, 116). On a much more common front are the increased opportunities for exposure of immunocompromised humans (genetically acquired, infectious acquired, age-related, etc.) to animals during home visits and visits to zoologic collections and petting farms (25,62, 118). Although opportunities for zoonotic infections have never been greater, the opportunities to detect infections early during the clinical course of disease and in carrier animals have also improved dramatically (71, 111, 132). It will be important for diagnostic epidemiologists and microbiologists to recognize the inherent danger of infectious agents and not to become complacent. The natural host, clinical symptoms in the host (if any), the clinical disease in humans, and control measures for each of the viruses described below are summarized in Table 1. Equine Morbillivirus

Infections

Description, Natural Habitat, and Disease in Animals Equine morbillivirus was .initially isolated from lung tissues of five of six horses and from kidney tissue of one human who died of acute respiratory illness in 1994 (120, 121, 148). The outbreak occurred in Queensland, Australia. The virus was tentatively identified as a member of the Paramyxoviridae on the

CUMITECH Table

32

1.

Ecology

Infectious

agent(s)

Diagnosis of selected

zoonotic

Natural animal reservoir(s)

infections Clinical

of livestock

symptoms host

and

in

of Zoonotic

Infections

3

wildlife

Accidental

host(s)

measures

Bats?

Unknown

Horses,

Hantavirus

Mice

Asymptomatic

Humans

ARDa,

Pigs, birds

Mild to severe respiratory disease Mild to severe respiratory, neurotropic disease Contagious ecthyma, mild to severe skin lesions

Humans

Respiratory

Humans

Conjunctivitis

Restricted to Australia, care in handling horses Good hygiene, control of rodent feces and aerosols Vaccination of high-risk subjects Good hygiene

Humans

Localized lesions, lymphadenopathy

Wear gloves, hygiene

Variable neurologic disease

Mammals, humans

Neurologic disease,

Unknown

Unknown

Horses, cattle, swine, humans

Control of animal exposure, vaccination of highrisk subjects Wear gloves, good hygiene

Filoviruses

Unknown

Unknown

Humans, nonhuman primates

Arenavirusesb

Mice,

Usually asymptoma

virus

Newcastle virus

disea

Parapoxvirus

Rabies

Sheep, cattle, goats, alpacas, camels Bats

virus

Vesicular stomatitis

C. burne tii

Birds

virus

rats

Sheep, goats, cattle, wildlife

a ARD, acute respiratory disease. b includes Junin (Argentina), Machupo

(Bolivia),

including

(Venezuela),

death

Influenza-like symptoms, oral lesions Acute hemorrhagic fever, death

Fever, hemorrhage, death

Humans

Generalized lymphadenopathy

Lassa

basis of electron microscopy of endothelial and syncytial cells lining the bronchial epithelium (121). The virus was subsequently confirmed to be a new morbillivirus within the family Paramyxouiridae on the basis of limited cross reactivity with rinderpest antiserum and comparative sequence analyses of a portion of the matrix protein gene (75, 121). The natural habitat for equine morbillivirus appears to have been restricted to the original sites of the two outbreaks (70, 121). Retrospective serologic studies of approximately 1,600 horses and 90 humans indicated that the virus was not highly contagious. It was speculated that the equine morbillivirus had emerged from its natural host of nonequine, nonhu-

death

Humans tic

Variable symptoms, from asymptomatic to abortion

Guanarito

Pneumonia, death

Control

Equine morbill ivirus

Influenza

humans

Primary clinical symptom(s) in humans

(West

Africa),

and other

good

Good hygiene when working with nonhuman primates and humans suspected of being infected Good hygiene, control of rodents, secretions, saliva, urine, aerosols; hyperimmune serum effective postexposure treatment Good hygiene when working with reproductive tissues from infected animals

viruses.

man origin (121). Because the two outbreaks occurred within one month of each other, approximately 1,000 km apart, animals capable of migrating between these areas were considered. Both birds and flying foxes, or fruit bats (Pteropus species), were considered (177). As of this date, no data are available for the occurrence of an avian source of equine morbillivirus. However, seropositive fruit bats have been identified (177). The prevalence of morbillivirus has been reported to be 9% in Australian bat species. Currently, it is proposed that fruit bats are infected with a bat morbillivirus (as yet to be isolated), which cross reacts with equine morbillivirus ( 177). Whether the bat morbillivirus is the cause of the acute respiratory disease

4

Evermann

et al.

in horses and humans must await further investigation. Equine morbillivirus is capable of causing severe respiratory disease in horses with low morbidity and high mortality (70, 121, 148). Horses typically will demonstrate elevated temperatures (42°C) and severe respiratory distress. Experimentally infected horses showed minimal clinical signs for up to 10 days, and then developed a severe disease of 2 days duration with high temperature and respiratory distress. Because the horses were euthanized at this time, the potential for recovery could not be determined. The predominant lesions observed in the horses were interstitial pneumonia with proteinaceous alveolar edema associated with hemorrhage, dilated lymphatic vessels, alveolar thrombosis, and necrosis of the endothelial walls of small blood vessels. Additional studies have indicated that equine morbillivirus has an extended host range in vitro, replicating in cell lines obtained from fish, reptiles, amphibians, and birds. The virus has also been demonstrated to infect domestic cats and guinea pigs, resulting in high mortality (148). Mode of Transmission to Humans The route by which humans became infected with the equine morbillivirus is unknown at this time. Three patients are known to have been infected, two of whom died (120, 121, 131). All three patients had extensive contact with horses antemortem, and in one case, the patient actually assisted at a necropsy without gloves, mask, or protective eye wear. Because other people had assisted in the necropsies of affected horses and did not become infected (lack of seroconversion and no clinical symptoms), direct contact with respiratory secretions of affected horses seems to be the most likely mode of virus spread. The possibility that the patients acquired the infection via the fruit bat rather than from the affected horses needs further investigation. Human Infections and Treatment Human infections with equine morbillivirus may take a variable course. The most severe is an influenza-like illness of several days duration from which one human died after six days in intensive care and one human recovered (120,121). The third case exemplifies the unpredictable nature of the virus in humans ( 13 1). The aseptic meningitis that initially developed shortly after the patient cared for two horses that died from equine morbillivirus was followed by a prolonged subclinical phase (13 months). After this period the patient was hospitalized because of a generalized tonicoclonic seizure, became unconscious with persisting fever, and died 25 days after admission. In all three cases, hospital staff contacts were retrospectively tested and determined to be seronegative (120,

CUMITECH

32

121, 13 1). There is no specific treatment for equine morbillivirus at this time- only supportive care. Diagnosis The diagnosis of equine morbillivirus infection has been primarily by serologic assays with the serum neutralization test (70, 121). Cultures of the virus from equine tissues collected at necropsy in Vero cells, or from humans at postmortem in LLC-MK2 and MRC.5 cells, have been reported. A diverse group of primers has been used to identify a broad array of paramyxovirusor morbillivirus-specific DNA sequences by reverse transcriptase-PCR (RT-PCR). The primers have been used to amplify specific sequences from the equine morbillivirus matrix protein gene to detect virus in cerebrospinal fluid from affected patients and to determine the phylogenic relationship of the equine morbillivirus to other members of the family Paramyxoviridae (63, 120, 121, 131). Infection Control Procedures Control of infection with the equine morbillivirus is difficult because the true host of the infection has not been elucidated, and there have been no further documented cases since 199.5. If the fruit bat is demonstrated to be the natural host of the virus, then the virus nomenclature will have to be modified to reflect this, and horses and humans will be regarded as incidental hosts (177). In the intervening time, care must be taken when handling horses with respiratory disease in the regions of Australia. There is no evidence to date that the virus has spread to other geographic areas. However, if the bat is the natural reservoir in nature, there may be comparable counterparts in other bat populations worldwide. Further epidemiological studies are warranted. Hantavirus

Infections

Description, Natural Habitat, and Disease in Animals Hantaviruses belong to the family Bunyauiridae and are characterized by a three-segmented negative-sense RNA genome and a lipid envelope containing two virus-encoded glycoproteins. The genus includes the causative agents of a group of febrile nephropathies known as hemorrhagic fever with renal syndrome (HFRS) observed in Europe and Asia, and the newly recognized hantavirus pulmonary syndrome (HPS) reported in North America (125). Hantavirus particles are spherical and 90 to 110 nm in diameter (127). These viruses replicate within the cytoplasm of host cells (113, 146) and can *be propagated in vitro in human endothelial cells ( 175). Worldwide, most human hantavirus infections have been associated with HFRS caused by several viruses within the genus. These include Hantaan virus present primarily in Asia; Dobrava virus in the Bal-

CUMITECH

32

kans; Puumala virus in Europe; and Seoul virus that has a worldwide distribution. Hantavirus pulmonary syndrome was first recognized in 1993 in the United States (50, 125). This syndrome is caused by at least three hantaviruses: Sin Nombre virus, previously referred to as the Muerto Canyon virus or the Four Corners virus (39); Black Creek Canal virus, which was associated with a case of HPS in Florida (82, 145); and the Bayou virus, identified in a case of HPS in Louisiana (84, 119). Rodents are the principal reservoir for all hantaviruses. Each member of the genus is associated with a specific rodent host. For example, the Seoul virus is found in the urban sewer rat (Rdtt~s noruegicus) (94), and the Sin Nombre virus is found in the deer mouse (Peromyscus maniculatus) (42). The antigenically distinct hantavirus in Florida is found in the cotton rat (Sigmodon hispidus) (37, and the rice rat Oryxomys pal+ris appears to be the rodent reservoir for Bayou virus (158). Most cases of human illness associated with hantaviruses in the United States have resulted from exposure to naturally infected wild rodents in rural settings. Hantaviruses do not cause apparent illness in their reservoir hosts, which remain asymptomatic for life (113). Infected rodents shed virus in saliva, urine, and feces for many weeks, but the duration of shedding and the period of maximum infectivity are unknown (93). The virus may also be present in the blood and organs of infected animals. Biting is thought to be an important mode of rodent-to-rodent transmission (42,128). Mode of Transmission to Humans Aerosols from infective saliva or excreta of rodents have been clearly implicated in the transmission of hantaviruses to humans (160). Laboratory transmission of hantaviruses from rodents to humans via the aerosol route has also been documented (95, 128, 162). Other potential routes of infection include ingestion, contact of infectious materials with mucous membranes or broken skin, and animal bites (49). Human-to-human transmission has been suspected but not proven (169). If human-to-h .uman transmission does occur, it is a rare event. Human Infections and Treatment The Hantaan serotype viruses cause severe HFRS. The Seoul serotype has been associated with a more moderate form of HFRS, while the Puumala serotypes are associated with a relatively mild form of HFRS. Regardless of severity, almost all cases of HFRS are characterized by sudden onset of high fever, chills, and myalgia. Hemorrhage and the degree of renal impairment vary. In severe forms, petechial rash often occurs on the face, body, and mucous membranes of the oral pharynx. As fever declines, hypotension be-

Diagnosis

of Zoonotic

Infections

5

gins, lasting a few hours to several days. Oliguria follows, and during this period hemorrhages may result from capillary fragility. The final stage is characterized by dieresis, which persists for days to several weeks. Recovery is slow but usually complete. Most deaths are due to disseminated intravascular coagulation during the oliguric phase, but shock resulting from hypotension is also a cause of mortality (74). The newly recognized HPS in the United States usually begins with fever, myalgia, cough, gastrointestinal symptoms, and headache. By the time patients seek medical attention, the most common physical findings are tachypnea, tachycardia, and hypotension. Laboratory findings include leukocytosis, often with myeloid precursors, increased hematocrit, thrombocytopenia, prolonged prothrombin and partial-thromboplastin times, an elevated serum lactate dehydrogenase concentration, decreased serum protein concentrations, and proteinuria. Rapidly progressive acute pulmonary edema develops in about 80% of patients. Death is invariably associated with profound hypotension (50), and the overall case-fatality rate is about 50% (83). Supportive and intensive care appears to be the most important treatment for HPS. This includes oxygen administered for hypoxemia, mechanical ventilation, and inotropic and vasopressive agents. Careful monitoring and fluid support for hemodynamic function are also required (27,50). Antiviral agents, such as ribavirin, are currently being investigated for efficacy in treating HPS (83). Analyses of the first 100 cases in the United States indicate that HPS has a distinct spring-early summer seasonality. Of these first 100 cases, 54% were male, 63% were Caucasian, 35% were Native American, and 2% were African American. The average age of these patients was 35 years (83). Diagnosis Several diagnostic tests for HPS are available from state laboratories and the federal Centers for Disease Control and Prevention. The tests include serology, antigen detection by immunohistochemistry, and RTPCR (27, 35, 78). There appears to be good concordance between the different diagnostic tests. In an analysis of 100 HPS cases, only two persons positive by immunohistochemistry had equivocal serologic findings, and nine seropositive persons had RT-PCRnegative blood clots and sera (83). Blood clots and sera are more likely to be RT-PCR-positive when obtained early in the course of infection, since viremia is probably short-lived (69). Infection Control Procedures The most important means of prevention is to avoid contact with wild rodents and their excrement. Rodents should be prevented from accessing homes, barns, cottages, and garages. When rodent-infested

6

Evermann

et al.

areas are cleaned, they should be ventilated before cleanup. Depending on the area to be cleaned, protective clothing, eye protection, gloves, and possibly facemasks, including high-efficiency particulate filters, may be necessary. Rodent excrement and trapped dead rodents should be sprayed with a disinfectant, and then disposed of in double-lined garbage bags (36). The lipid envelope of hantaviruses makes them susceptible to most disinfectants, including dilute hypochlorite solutions, detergents, ethyl alcohol (70%), and most general-purpose household disinfectants (139).

Influenza Description, Natural Habitat, and Disease in Animals Influenza virus represents one of the most adaptable viruses affecting both humans and animals (167). The virus belongs to the orthomyxovirus family, and like many viral infections, the clinical manifestations were recognized early in recorded history. The virus was first isolated in 1933 by using the ferret as an experimental host. The virus was subsequently identified as type A influenza virus, with other antigenic types identified in 1940 (type B) and 1949 (type C), respectively (46, 150). The influenza viruses are pleomorphic enveloped Vl ruses ranging in size from 8 0 to 120 nm. The virions of types A and B strains contain eight structural proteins and eight nonsegmented single-stranded RNA molecules of a negative polarity (46). An excellent description of the viruses was reported by Couch and Kasel(46). Briefly, the viral core contai .ns the nonseg-mented ssRNA molecules and three polymerase proteins: PBl, PB2, and PA. These proteins are in close proximity to the nucleoprotein, which serves to protect the RNA molecules, and provide the backbone for the helical-shaped nucleocapsid. The nucleoprotein carries the type-specific antigens that are used to distinguish the three types (A, B, and C). Influenza types A and B code for two m ajor vi rion surface glycoproteins, the hemagglutin .in v-w and the neuraminidase (NA). These proteins are essential for attachment to host cell receptors and subsequent egress from infected cells (46). Although influenza type C shares many structu .ral properties wi th types A and B, some major differences are worthy of note. These include the presence of a single multifunctional envelope protein, the hemagglutinin-esterase (HE), which facilitates virus attachment to host cell receptors, induction of cell membrane fusion, and destruction of host cell receptors. Influenza type C has only seven RNA gene segments (46, 150). The nomenclature for identifying strains of influenza virus is based on guidelines published by the World Health Organization. A thorough review of

CUMITECH

32

classification (150). has been recently published Briefly, the name given to each influenza virus includes type (A, B, or C), host of origin, geographic origin, strain number, year of isolation, and the antigenic subtype designations of the HA and NA glycoproteins. When host of origin is not included, it is assumed that the host was human. An example is the recently proposed strain identification of the virus that caused the outbreak of “Spanish” influenza in 1918 and 1919. This strain is A/human/South Carolina/l/18 (HlNl) (157). Type A influenza occurs worldwide. It is a highly contagious, acute respiratory illness associated with high morbidity and low mortality. Type A influenza is most often recognized in humans, equine, swine, and multiple avian species. Types B and C influenza are primarily restricted to humans, in whom the clinical signs are similar to those of type A influenza, but the attack rate is not as high (150). The mammalian-origin type A influenza viruses are considered to be relatively species specific, with each respective mammalian species serving as its own primary reservoir. Interspecies transmission of type A influenza between humans and swine has been the subject of numerous reviews (100, 150, 159, 167). Although not well documented, there is information that interspecies transmission has occurred between avian and mammalian species (turkey influenza A and swine influenza A) (85). Genetic reassortment has been reported to occur between swine influenza (HlNl) and avian influenza (HlNl). A recent report indicated that type C influenza of humans has been isolated from swine in China (86). On the basis of studies with monoclonal antibodies to the hemagglutinin-esterase glycoprotein and Tl-oligonucleotide fingerprinting, the viruses are closely related. It was not determined whether the viruses were being transmitted from swine to humans or from humans to swine (86). Type A influenza infections of equine, swine, and avian species have resulted in a range of clinical signs from asymptomatic carriers to high mortality (9, 51, 52). In horses, type A influenza is an acute febrile respiratory disease. Two antigenically distinct strains are known to affect horses, A/equi/l/Prague/l956 and A/equi/2/Miami/l963. Both strains have remained relatively stable; however, antigenic drift has been detected in the A/equi/2 virus. While there is close antigenic relationship with human type A influenza, there is no indication to date that there has been cross-species spread from horses to humans (51 ). Swine influenza is an acute, highly contagious febrile respiratory di sease with high mor bidity and 1.ow mortality. Type A influenza of swine m .ay be observed throughout the year, but in the north central United States it is most often observed during the late fall and

CUMITECH

32

early winter months. The HlNl influenza virus that is endemic in the United States can be distinguished antigenically from the swine influenza virus that circulates in Europe (100, 150). The European virus is more closely related to the type A influenza that infects birds. The HlNl swine influenza virus in the United States has remained stable since it was first identified in 1930. The swine influenza virus is known to be transmissible to turkeys and people (150). Avian influenza, also known as fowl plague, was recognized in 1878 as the cause of severe losses in the poultry industry (9,85). It was not until 1955 that the virus was actually identified as a type A influenza virus. Since 1960, the predominant disease host has been the turkey in the United States (9, 85). Disease signs include swollen head, visceral hemorrhages, and greenish diarrhea. Layers frequently exhibit yolk peritonitis due to ruptured ovules. Avian influenza virus is known to occur as an intestinal infection of many species of waterfowl and seabirds and is usually asymptomatic. It is generally accepted that wild birds serve as reservoirs for avian influenza infection of domestic poultry (9, 85). Mode of Transmission to Humans Influenza viruses are most effectively spread via secretions from the nasal-pharyngeal region by saliva, aerosol droplets produced by coughing, and sneezing (46,150). Exposure may also occur through contaminated fomites. The most apparent zoonotic link to date has been between swine and humans (52,85,86, 100, 150). On-the-farm contact by handling infected animals, being in closed barns with improper ventilation, and fomite transmission may also result in exposure. Recent evidence suggests that avian influenza virus may also be transmitted to humans. In addition, a link between turkey influenza virus and swine infection has been made, as has a link between swine influenza and human infection. There may be a common but undefined connection between human, swine, and avian influenza viruses that remains to be elucidated (85, 100). Human Infections and Treatment Several antiviral compounds are available for treatment of type A influenza virus infections (4 86). Amantadine can be used in humans at high risk who have not had prior vaccination. Infections can be curtailed (40 to 90%) and symptoms reduced (70 to 100%) if amantadine is administered within the initial 48 h clinical signs appear. Rimantadine, an analog of amantadine, has similar prophylactic and therapeutic properties as amantadine with fewer side effects (46). Diagnosis The diagnosis of influenza in human, equine, and swine populations is based on a combination of clinical symptoms and laboratory diagnostic assays (46,

Diagnosis

of Zoonotic

Infections

7

51, 52). The majority of influenza outbreaks have a high attack rate and result in a population of infected humans or animals with rhinitis, serous nasal discharge, and general malaise (46, 150). Laboratory diagnosis involves virus isolation in cell culture (monkey kidney cells, chicken embryo fibroblasts, or Madin-Darby canine kidney cells) and/or embryonating chicken eggs. Virus isolates are identified by fluorescent antibody, enzyme-linked immunosorbent assay (ELISA), and hemagglutination inhibition. RT-PCR has been applied in some diagnostic laboratories to increase the sensitivity of the assays. Serologic assays may be used for diagnosis with acute and convalescent serum samples. Both the complement fixation and the hemagglutination inhibition assays are routinely used for this purpose (46). Infection Control Procedures Control of influenza virus infections is difficult because of the widespread occurrence of asymptomatic infections in the human and animal populations (9, 46,51,52). The multiple animal species in the ecology of the infection in nature adds to the complexity of control (159). Partial control of clinical symptoms can be obtained by the use of inactivated vaccines in humans and animals at high risk for developing the disease. Inactivated vaccines for types A and B influenza are available for humans (150). Inactivated vactines for type A influenza viru .ses are available for horses, swine, and poultry (9, 5 1, 52). It is generally regarded that these vaccines provide short-term protection *from clinical symptoms but do not prevent infection. Newcastle

Disease

Description, Natural Habitat, and Disease in Animals Newcastle disease has been recognized as a major cause of disease in poultry since 1926 (10). The disease is caused by the most economically important of the nine known avian paramyxovirus serotypes, paramyxovirus type 1, commonly referred to as Newcastle disease virus (NDV). The virus contains a single-stranded RNA, has a helical symmetry, and has hemagglutinin, neuraminidase, and hemolysin viral proteins. The natural habitat for the virus is avian species and is carried in the upper airways of asymptomatic carrier birds. Three main pathogenic types of NDV are responsible for infections. These infections may result in severe respiratory and neurologic symptoms, visceral hemorrhages, and high mortality or are asymptomatic. The virus strains causing these infections are commonly referred to as velogenic, mesogenie, and lentogenic, respectively ( 10, 81, 88). The disease in avian species occurs in outbrea ,ks, with large numbers of birds affected (10). The velo-

8

Evermann

et al.

genie NDV may result in edema of the neck and head, severe respiratory symptoms, green diarrhea, and mortality of 100%. The mildest form of the disease is caused by the enteric lentogenic strains, which infect the gastrointestinal tract and are usually subclinical. Such strains have been recovered from chickens in Australia and portions of Europe and from migratory waterfowl in the United States. Mode of Transmission to Humans There are two sources of human infections: The first is contact with naturally infected birds, and the second is acquisition of the virus from modified live vaccines ( 10,8 1). The virus is spread by aerosol and by fomites to the oropharyngeal region and to the eyes. Ingestion of infected meat cannot cause human disease. Human Infections and Treatment Human infections from NDV are usually considered an occupational risk and are most common among poultry farm workers, veterinarians, and people who are rehabilitating wild birds in captivity (81, 88). Patients with generalized NDV infections have influenza-like symptoms, including a rise in temperature, chills, headache, and pharyngitis. In rare cases, patients may develop bilateral conjunctivitis, photophobia, palpebral edema, and general apathy. People are susceptible to all three types of NDV, including the lentogenic vaccine strains. There is currently no treatment for human NDV infection. Diagnosis Human NDV infection may be diagnosed by isolating virus from conjunctival or nasopharyngeal secretions, saliva, or urine in a wide variety of susceptible cell lines, such as Vero cells, or by inoculating embryonating chicken eggs (88). Serologic diagnosis of human NDV is not routinely done, since there are no commercially available reagents and antibody production in humans is not consistent (8 1, 8 8). Infection Control Procedures Control of NDV in poultry involves strict adherence to quarantine before birds enter the United States and vaccination where acceptable (10). Prevention of human infections involves use of proper safeguards when affected birds are handled and when spray vaccines are used. Precautions should be taken to protect eyes from aerosols and fomites. The use of a face mask to protect against ocular and respiratory exposure is recommended (81, 88). Parapoxvirus

Infections

Description, Natural Habitat, and Disease in Animals The genus Parapoxvirus of the family Poxviridae contains three viruses of domestic animals that can cause infections in humans. These are bovine papular sto-

CUMITECH

32

matitis virus, pseudocowpox virus of cattle, and the orf virus of goats and sheep (54). A seal parapoxvirus that caused human infections has also been described (68). The genomes of these viruses consist of linear double-stranded DNA ( 144). Bovine papular stomatitis virus probably has worldwide distribution. Cattle are the natural host for this virus and appear to be the only susceptible species other than humans. The incidence of disease in cattle is not well known. The virus is probably transmitted by direct contact between animals, and it enters the body through breaks in the skin or through the mucous membranes. Infections in cattle may be clinically inapparent or cause a mild, afebrile disease characterized by localized proliferative lesions in and around the mouth. Occasional outbreaks in cattle are characterized by fever and diarrhea, in addition to localized oral and teat lesions. The disease is observed most often in young cattle and produces hyperemic lesions in the nostrils, palate, or inner surface of the lips. These foci progress into papules and ultimately into papulomatous plaques. Although individual lesions may last for only a day or a few weeks, lesions can be found in various stages of development on a single animal, causing the course of the disease to persist for several months. Occasionally morbidity may be high within a herd, and cyclic reinfection can occur. Clinical disease may delay development in very young animals, but in general the disease is not considered to have significant economic impact. Lesions in cattle *must be differentiated from other vesicular diseases that are of economic concern (1,54, 74). Like bovine papular stomatitis virus, pseudocowpox virus is distributed worldwide. Serologic studies in the United States indicate that most infections in cattle are clinically inapparent. In countries where milking is done by hand, human disease, referred to as milkers’ nodules, is common. Whereas bovine papular stomatitis virus occurs in dairy and beef cattle, pseudocowpox virus infections are limited to dairy cattle. This is due to the mechanical mode of transmission of pseudocowpox virus from cow to cow via milkers’ hands, teat cups, or milking machines. Lesions are similar to those associated with bovine papular stomatitis virus except that they are located primarily on the udder and teats. In nursing calves, lesions of the buccal mucosa may be found (3,143). Contagious ecthyma, also known as contagious pustular dermatitis or stomatitis, sore mouth, scabby mouth, and orf, has a worldwide distribution and has been diagnosed in sheep, goats, alpacas, and camels. The disease has also been observed in dogs and some wild species. Lesions appear on the skin of the lips and sometimes around the nostrils and eyes. Ewes suckling affected lambs often develop udder lesions. Contagious ecthyma can be an economically important

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32

disease as lesions in or on the mouths of lambs can interfere with eating, and open sores can result in secondary infections and myiasis (2, 54, 115). Mode of Transmission to Humans In humans parapoxvirus infections are an occupational risk usually acquired by direct contact with infected animals (54, 74). Humans may also become infected with the orf virus by contact with contaminated objects or wool (2). The viruses enter through breaks in the skin, usually on the hands, and are a result of handling animals, such as through milking or examining the animal’s mouth (l-3). Human Infections and Treatment The incubation period varies from 3 to 8 days. The cutaneous lesions in humans from parapoxvirus infections share some common characteristics. Lesions begin as erythematous papules that develop into vesicular or pustular foci or, as is likely in bovine papular stomatitis virus infections, verrucous nodules ( 1). Pseudocowpox lesions are highly vascular, tend not to ulcerate, and are usually painless, but are often pruritic (54). Orf lesions may be painful and may be associated with a low-grade fever and swelling of the draining lymph nodes (54). These infections in people are self-limiting, and lesions usually resolve within 4 to 6 weeks (l-3,54). There is no specific treatment for parapoxviral infections. Diagnosis A diagnosis in humans is usually based on clinical findings and a history of exposure to infected animals. The diagnosis can be confirmed with electron microscopy or virus isolation. The virus can be isolated in tissue culture with bovine or ovine embryo kidney or testis cells (2, 54). Infection Control Procedures Effective control measures to prevent transmission of the viruses to humans minimize disease in animals and use good hygiene practices when working with diseased animals. Hygiene practices include protecting skin wounds, wearing gloves, and washing hands. Vaccination is sometimes considered to control contagious ecthyma in sheep. The most commonly used vaccine is a suspension of pulverized virulent scabs in a glycerinated solution (crude vaccine) that is applied by scarification in the axilla. Crude vaccines, however, perpetuate the infection in the environment, and vaccination failures can occur. An attenuated cell culture vaccine has been developed, but its use is limited (2). Persons administering vaccines should wear gloves and wash hands immediately after exposure. Because bovine papular stomatitis is of minimal economic concern, no specific control measures in animals are recommended. There is no vaccine against pseudocowpox. Control of pseudocowpox in cattle

Diagnosis

of Zoonotic

Infections

relies on the use of good hygiene during milking 115,143).

9

(74,

Rabies Description, Natural Habitat, and Disease in Animals Rabies virus is a member of the genus Lyssavirus of the family Rhabdoviridae (174). It has a nonsegmented, negative-stranded RNA genome. Virions contain five proteins, including a single surface glycoprotein. It is the surface glycoprotein that is the immunogen in the vaccinia-rabies recombinant vaccine used to control rabies in wildlife populations and recently approved for use in raccoons in the United States (97). The genus Lyssavirus consists of six genotypes that have a high degree of amino acid and nucleotide sequence homology with rabies virus and result in clinical disease indistinguishable from rabies encephalitis. These viruses can be differentiated by monoclonal antibodies, virus-specific antiserum, and genetic typing (24, 87). Reservoirs for rabies virus are found worldwide except for Australia, Hawaii, Japan, United Kingdom, and the Antarctic continent. The virus is maintained by interspecies transmission in a wide variety of carnivores and bats. The other lyssaviruses have a much more limited geographic and reservoir host distribution, and only endemic levels of transmission have been observed (153). Within broad geographic regions rabies infections in terrestrial mammals are linked to distinct virus variants that can be identified by reactions with monoclonal antibodies (152) or by characteristic nucleotide substitutions (155). A specific rabies virus variant is maintained in a particular region through animal-to-animal transmission within a single species. Spillover infection to other terrestrial animal species may occur, but these cases are sporadic and rarely result in a ny sustained intraspecific transmission (153). Once established in an area, the virus can be maintained within a species at endemic levels for decades. Depending on the geography and contiguous susceptible animal populations, the affected area may enlarge over time. For example, the raccoon rabies epizootic recognized in the 1970s in the mid-Atlantic states has now converged with the raccoon reservoir in the Southeast (31,38, 79). In the United States there are several long-standing terrestrial wildlife rabies reservoirs and a few expanding terrestrial epizootics. As stated above, one geographic boundary is the long-standing raccoon reservoir in the southeastern states that has now merged with the raccoon epizootics in the mid-Atlantic and northeastern states (31, 38, 146, 172). This single viral variant now exists in raccoons throughout the entire eastern United States. Additional long-standing

10

Evermann

CUMITECH

et al.

foci include the red and arctic foxes in Alaska, the New England states, and parts of Canada (122,156). Two long-standing and distinct viral variants are recognized in gray foxes in small reservoirs in Arizona and Texas (152). Three rabies viral variants exist in three distinct skunk populations in California, the north central United States, and the south central United States ( 129). A recently recognized epizootic of a rabies variant in coyotes in south Texas is a result of transmission from a domestic dog reservoir along the Texas-Mexico border (43). Overlying rabies reservoirs in terrestrial mammals are multiple, independent reservoirs in several species of bats (150,154). Although distinct viral variants can be identified for the different bat species, geographic boundaries are not defined in bats due to the migratory nature of some species (153). In the United States only Alaska and Hawaii are free of bat species affected by rabies. Mode of Transmission

to Humans

Human rabies results from exposure to the infectious saliva of rabid animals introduced by bites, or more rarely, by contact with abraded skin or mucous membranes (18). There are a few documented cases of human rabies acquired by aerosol transmission from exposures in bat caves (44). Aerosol transmission has also been observed in laboratory accidents (29). Human-to-human transmission has occurred but is extremely rare. These include transmission resulting from cornea1 transplants, contact with human saliva, transmission to an infant from milk, and transplacental transmission ( 18). Worldwide, most human rabies cases are due to exposure to domestic dogs as a result of numerous urban canine reservoirs. In countries where canine rabies has been controlled or eliminated and where wildlife rabies reservoirs exist, the number of human cases has been reduced to very low levels (4). Herbivores and other nonbiting animals, rodents, and lagomorphs do not play a role in the epidemiology of rabies and rarely result in human exposure (4). Although bats are responsible for a relatively small portion of cases in terrestrial animals (90), bat-associated viral variants account for a disproportionate number of the more recent human rabies cases in the United States (155). Of concern is that in most of these cases there is no history of animal bite exposure, although contact with a bat is usually documented. It is possible that bites from the small, sharp teeth of insectivorous bats go unnoticed. Human

Infections

and Treatment

The incubation period in naturally infected animals and humans is usually a few to several weeks (18) but may be 6 months or longer (23). In humans the incubation period is usually 3 to 8 weeks, but very

32

short incubation periods of 4 to 14 days have been recorded following severe bites on the face, neck, and hands (18). Although unusual, some epidemiologic evidence in humans suggests incubation periods of several years (154). Prodromal symptoms may develop that include pain, tingling sensations, pruritus, or paresthesia at the site of exposure. These localized sensations may remain fixed or progress to trembling or weakness in the affected limb. Early symptoms are variable and nonspecific and resemble the flu. These include low-grade fever, chills, malaise, weakness, anorexia, sore throat, and cough. Early central nervous symptoms may include restlessness, apprehension, irritability, and headache. Most cases rapidly progress to a hyperactive state with increased sensitivity to tactile, visual, or auditory stimuli. Increased reflexes, lacrimation, perspiration, and salivation are also noted. Hydrophobia may develop and is considered pathognomonic in this phase of the disease. The hyperactive phase can last 2 days to up to a week and may reflect supportive care. Because of the variability in damage to the central nervous system, a wide variety of other symptoms may may develop. These may may include facial or vocal cord paralysis or continuous salivation and lacrimation. Paralytic or depressive symptoms may become apparent and dominant at any point in the course of the disease and may progress to stupor and coma. Although supportive care in clinical disease may extend life, rabies in all animals and humans is invariably fatal (18). Initiation of specific immunotherapy after the onset of clinical disease by administering vaccine, immune globulin, or monoclonal antibodies has not been sucure treatment soon after excessful (126). (126 ). Postexpos Postexposure posure and before clinical disease, however, is very effective in preventing disease. Postexposure treatment consists of local treatment of the wound and passive and active immunization of the individual. Wound treatment immediately after exposure is extremely important and can prevent many cases of rabies by locally destroying or eliminating the virus. In addition to washing the wound with soap and water, infiltrating the wound with rabies immune globulin is also effective in helping to prevent infection. Vaccination should be started as soon as possible to ensure specific systemic immunity before the virus reaches the central nervous system. Current guidelines from the Centers for Disease Control and Prevention for postexposure treatment of an individual not previously vaccinated are wound treatment, intramuscular human rabies immune globulin with one-half the dose infiltrated around the wound or wounds, and a series of five vaccinations on days 0,3,7,14, and 28. If the individual has been previously vaccinated, human rabies immune globulin is not given and vaccinations

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32

are given on days 0 and 3 only. Preimmunization is limited to people at high risk as discussed below (30). Diagnosis Antemortem tests for rabies in animals and humans are only reliable if positive and do not affect patient outcome. Although antemortem tests lack sensitivity, they are frequently used in suspected human cases to reduce exposure to other people. In humans there is no evidence of an immune response to rabies infection until late in the clinical course (153). Detection of specific antibodies in the cerebrospinal fluid is diagnostic regardless of vaccination history (7). A direct immunofluorescent antibody (IFA) test for antigen in nuchal or facial skin biopsies or brain biopsies can be done. Viral isolation from saliva may be attempted in cell culture or laboratory mice (18). Molecular techniques such as RT-PCR ha ve been use d in antemortem diagnosis, but there is no evidence that viral RNA is any more widely distributed or accessible than viral antigen until late in the clinical course (80). The preferred postmortem diagnostic test for rabies in animals and humans is the direct IFA for viral antigen in brain tissue. Histologic stains for Negri bodies detect only 50 to 80% of IFA-positive samples and are no longer used to confirm a rabies diagnosis. However, Negri bodies have been detected on histologic examination of brain tissue from unsuspected cases, thus resulting in a diagnosis later confirmed by IFA. Because the IFA test is rapid, sensitive, specific, and relatively inexpensive, molecular techniques are not routinely used for postmortem rabies diagnosis, but have been used to confirm equivocal IFA results and for molecular epidemiology (108, 122, 153). Infection Control Procedures The most effective measure for preventing human rabies is controlling rabies in animals (18). A major canine vaccination effort in the 1940s and 1950s in the United States, along with stray animal and population control programs, eliminated the rabies reservoir in dogs and dramatically reduced the number of human rabies exposures and deaths (17). As rabies cases in domestic animals have declined, reported cases in wild animals have increased significantly (90). Efforts to control rabies in wildlife species have proven to be more difficult than those in domestic animals. Population reduction methods have not been successful in eliminating rabies from any sylvatic reservoir (1.53). Several programs to vaccinate wildlife populations have been implemented. Oral bait vaccines were effective in controlling or eliminating rabies in foxes in some areas of Europe, but the geographic areas of interest were small compared to the major rabies wildlife areas in the United States. The initial public health response to epizootics of wildlife rabies in the United States has been to interrupt the trans-

Diagnosis

of Zoonotic

Infections

11

mission of rabies from the terrestrial wildlife species to humans through vaccination and confinement of domestic animals. This approach has been successful in preventing human disease. However, as certain wildlife reservoirs expand, such as the recent extension of raccoon rabies to include the entire eastern United States, there is renewed interest in trying to eliminate rabies in the wildlife reservoir. Although no human rabies cases have resulted from the raccoon epizootic to date (38), the need for human postexposure prophylaxis has markedly increased due to increased exposure to rabid domestic animals or potentially rabid raccoons ( 161). Vaccination programs targeting wildlife populations are proposed or under way to control raccoon rabies in the eastern United States and coyote rabies in Texas (97, 114, 161). In addition to animal vaccination programs, specific recommendations of the National Association of State Public Health Veterinarians address postexposure management of domestic animals and management of animals that bite humans (41). Unvaccinated dogs and cats exposed to a rabid animal should be euthanized or placed in strict isolation for 6 months and vaccinated 1 month before release. Unvaccinated livestock exposed to rabies should be slaughtered or isolated for 6 months. Dogs, cats, and livestock currently vaccinated and exposed to a rabid animal should be vaccinated immediately and observed for 45 days for signs of rabies. A healthy dog or cat that bites a person should be confined and observed for 10 days for signs compatible with rabies because the virus appears in the saliva after replication in the central nervous system at most 10 days before the onset of clinical signs (153). If healthy at the end of the observation period, the animal should be vaccinated if not currently vaccinated. Previous vaccination of other animals may not preclude the necessity for euthanasia and testing if the period of virus shedding prior to onset of clinical signs is unknown for that species. Bats present special problems for rabies prevention programs because of lack of recognition of possible exposures. A child in the state of Washington died of rabies due to a bat viral variant (40). A complete history at the time of antemortem diagnosis did not reveal a clear history of direct contact with a bat, although a bat had been found in the bedroom of the child. Public health officials were not consulted on this case when exposure occurred, but they admitted that postexposure treatment probably wou .ld not have been recommended on the basis of the inform .ation provided. Because of this case, Washington state public health officials have adopted a “bat in the bedroom” policy. This policy states that postexposure prophylaxis should be initiated even if there is no history of direct contact with a bat if the person is in

12

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et al.

the same room with a bat and if the person is unconscious (or unsupervised if a child) during any of this time (165). Clearly, if the bat is available, IFA testing of the brain is recommended in any suspect exposure to properly guide postexposure treatment. Preimmunization against rabies is recommended for people at high risk, including veterinarians, animal handlers, laboratory workers handling the virus, and persons living in areas where canine rabies is endemic (30). People who have recently been vaccinated against rabies are advised to not give blood for a few months because of possible false-positive human immunodeficiency virus results on the enzyme immunoassay screening test (135). In addition to preimmunization, routine laboratory handling of infected material requires biosafety level 2 practices and facilities. Biosafety level 3 may be indicated for activities with a high potential for aerosol production and when producing large quantities of infectious virus (33).

Vesicular Stomatitis Description, Natural Habitat, and Disease in Animals Vesicu lar stomatitis is a viral disease of cattle, horses, swine, and some wild vertebrates caused by a group of viruses belonging to the genus Vesiculovirus of the family Rhabdoviridae (178). These are enveloped viruses composed of a single strand of negative-strand RNA (28). In the United States, disease is caused by one of two distinct serotypes of the virus: vesicular stomatitis virus New Je&ey and vesicular stomatitis virus Indiana. A single surface glycoprotein is the major antigenic determinant that distinguishes these two major serotypes (96). Vesicular stomatitis has, considerable geographic and host diversity. It occurs only in the Western Hemisphere and is endemic in tropical and semitropical forests, particularly in Central and South America. Sporadic outbreaks occur in the more temperate regions of the Western Hemisphere (74). Vesicular stomatitis viruses have been isolated from a number of vertebrates, including rodents, opossum, mules, horses, cattle, swine, and humans, and from several insects, including sandflies and mosquitoes (56, 141, 166). The natural history of vesicular stomatitis is obscure. Periodic outbreaks tend to occur at lo- to M-year intervals, usually during warm weather. The reasons for this outbreak interval are unclear. The wild host or hosts where these viruses persist in enzootic areas have not been identified. Because of the geographic distribution and seasonality of epizootics, it has been suggested that insects may be important in transmitting the virus to animals (164, 166). The incubation period in animals is from one to a few days (166). Vesicular stomatitis must be differentiated from foot-and-mouth disease in animals sus-

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32

ceptible to both viral diseases, as their symptoms are similar. The disease is characterized by a short febrile period, usually accompanied by excessive salivation in horses and cattle. In swine, the initial clinical sign is often lameness (65). Papules and vesicles appear on the tongue, gums, palate, lips, and udder, in interdigital areas, and on the coronary band. In swine, lesions are often seen on the snout (166). Recovery usually occurs in about a week, but secondary bacterial infections can be a complication. The disease can cause significant economic losses, primarily in cattle and swine. Case fatality rate is low (5). Viremia is not detectable in cattle, horses, or swine but has been demonstrated in experimental infections in laboratory animals (166). The disease caused by the New Jersey type virus is usually more severe than the disease resulting from the Indiana type (5). Subclinical infections have also been demonstrated (164,166). Mode of Transmission to Humans Vesicular stomatitis in humans has occurred under natural circumstances associated with both epizootic and enzootic conditions, in persons working with experimentally infected animals, and in people handling viral material in the laboratory (142). Under natural conditions relatively intimate direct contact with infected animals is associated with risk of infection. Thus, disease is described most often in veterinarians and in people who work with livestock. The virus may be present in the saliva or the exudate or epithelium of open vesicles. The virus is not transmitted in milk, and infections through the oral route have not been demonstrated (5). Infection can result from direct transmission by aerosol, by infection through mucous membranes - especially the conjunctiva and by percutaneous inoculation of the virus through open wounds or injection (142). Human infection by arthropod transmission is also a possibility but has not been clearly demonstrated. Human Infections and Treatment Humans are susceptible to both the New Jersey and Indiana strains of vesicular stomatitis virus. The incubation period is 1 to 2 days. Vesicular stomatitis in humans usually presents as an acute, flu-like disease with fever lasting 1 to 2 days. In addition to fever, symptoms include headache, retro-ocular pain, myalgia, weakness, and chills (66). Some individuals develop pharyngitis, nausea, and vomiting (55). A minority of patients develop vesicular lesions, which appear in the oral cavity, lips, or nose or on the hands (133). The disease is usually self-limiting, lasting only a few days to a week (55). Rarely is hospitalization required. Treatment is limited to supportive care. Diagnosis Diagnosis of vesicular stomatitis in humans is based on serology, with a fourfold or greater increase in

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specific antibody between an acute and a convalescent blood sample taken 2 weeks apart. The complement fixation and serum neutralization tests are most frequently used. It is difficult to isolate the virus from blood as viremia lasts a short time. In animals with acute disease the virus can be isolated from nasopharyngeal and throat swabs, vesicular fluid, or epithelial tissue from the base of ruptured vesicles (5,166). Cell culture systems that use Vero cells or primary cell lines are most productive. A timely diagnosis in domestic animals is very important, as vesicular stomatitis must be differentiated from foot-and-mouth disease in ruminants and swine. Infection Control Procedures Although a number of vesicular stomatitis virus vaccines have been evaluated for use in animals (60,92), vaccination is not routinely practiced (60). Vaccines are not available for use in humans (74). Measures to prevent natural transmission from animals to humans include good hygiene practices when working with animals, wearing gloves and protective clothing when handling suspected or confirmed infected animals, and isolating infected animals showing clinical signs. Natural immunity does not persist, and there is no cross-protection between strains (74). In the laboratory biosafety level 3 practices and facilities are recommended when handling infected material. Gloves and respiratory protection are recommended for necropsy of infected animals (34). Filovirus

Infections

Description, Natural Habitat, and Disease in Animals The filoviruses were initially recognized in 1967 with the outbreak of a previously unknown viral hemorrhagic disease in animal handlers in Marburg, Germany (110). The viruses were acquired from exposure to tissues and blood from wild African green monkeys (Ceropithecus aethiops) imported into Europe from Uganda (110). Subsequent outbreaks of disease in humans occurred in Zaire in the vicinity of the Ebola River. The viruses are enveloped, contain nonsegmented negative-stranded RNA, and are separated into two antigenic types: Marburg and Ebola (53). The viruses are among the largest known viruses, with lengths of up to 14,000 nm reported (110). Extensive biochemical and genetic analyses have been conducted on the viruses. Marburg viruses have little genetic variability, while Ebola viruses have been subdivided into at least three distinct subtypes. The subtypes have been identified on the basis of the location from where they were first isolated: Ebola/Sudan, 1976; Ebola/Zaire, 1976; Ebola/Reston, 198971990 (53) The natural habitat for filoviruses is controversial.

Diagnosis

of Zoonotic

Infections

13

It has been possible to associate an index human case with imported nonhuman primates, but the origin in nature and the natural history of Marburg and Ebola viruses remain a mystery (53). It is generally concluded that the viruses are transmitted to humans from ongoing life cycles in animals or arthropods. Species such as guinea pigs, primates, bats, and hard ticks have been proposed as natural hosts on the basis of serologic studies. However, because of the lack of specificity of the indirect immunofluorescence assay, the results have been difficult to interpret (53). All attempts to date to backtrack the reservoir for human index cases in Africa or from epidemics in monkeys in Africa and the Philippines have been unsuccessful. Nonetheless, wild monkeys are still considered to be an important source for the i ntroduction of filoviruses into the human popula tion (53). Natural disease in animals with the filovirus has been difficult to document. African green monkeys inoculated experimentally with Marburg virus all died. Naturally occurring illness and death in cynomolgus monkeys in a primate quarantine facility in Virginia were documented with Ebola/Reston ( 110). Subsequent outbreaks of Ebola/Reston in the Philippines in 1989 and 1990 occurred in cynomolgus monkeys. No human illness was documented for either the Reston or the Philippine outbreaks (53,110). Evidence for an Ebola virus infection among captured monkeys in the Philippines indicated that filoviral antigen could be detected in 53% of the monkeys dying within the facility. Serologic studies on other monkeys held at the facility showed that a high percentage of clinically normal monkeys were seropositive for filovirus antibodies. In 1992 there were two outbreaks of Ebola hemorrhagic fever in chimpanzees kept in a semi-wild zoological park habitat in Ivory Coast, Africa (53, 110). More recently there have been three outbreaks of Ebola hemorrhagic fever in Gabon (61). Deaths of nonhuman primates were associated with all three outbreaks. All the primary human patients were infected while butchering dead chimpanzees (61). Mode of Transmission to Humans The spread of filoviruses to humans appears to have a high association with wild monkeys and perhaps bats. Once an index case is presented in the human population, transmission to close family members and hospital or medical staff may occur. Person-to-person spread by intimate contact is the main route of infection (53,110). Epidemics of Ebola virus disease eventually terminate due to death of theninitial patient and inefficient spread of the viruses. Diagnosis Extreme caution should be taken if filovirus infection is part of the differential diagnosis. The best recom-

14

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Table

2.

Virus

name

Junin Machupo Guanarito Lassa

Arenaviruses

et al.

CUMITECH causing

hemorrhagic Natural

fevers

in human9

host

Geographic

Vesper mouse (Calomys muscu/bws) Vesper mouse (Calomys ca//osus) Cotton rat (Sigmodon hispidus) Multimammate rat (Mastomys natalen&)

a Modified from reference 77. Although there are 15 recognized in humans. These include the above-mentioned cause disease which has a worldwide distribution range (77).

32

members of the family viruses and lymphocytic

mendations involve consultation with appropriate containment laboratories that have biosafetv level 4 facilities (77). These include: 1 . Special Pathogens Branch Division of Viral and Rickettsial Diseases Center for Infectious Diseases Centers for Disease Control and Prevention Atlanta, GA 30333 Phone: (404) 639-1115 Fax: (404) 639-l 118 2 . U.S. Army Medical Research Institute of Infectious Diseases Headquarters, Fort Detrick Frederick, MD 21702-5011 Phone: (310) 619-2772 Fax: (301) 619-4625 In the interim period the use of strict barrier nursing procedures (e.g., gown, gloves, and face mask) should be required. These procedures have been shown to be sufficient to interrupt transmission (53). Human Infections and Treatment The incubation period for the filoviruses ranges from 3 to 10 days. The incubation period for infections by Ebola/Sudan may be slightly longer than for the more lethal Ebola/Zaire strain. The infection-to-illness ratio for Marburg and Ebola viruses is almost 1: 1, since few if any asymptomatic infections have ever been documented. This is in contrast to Ebola/Reston, as all individuals to date who have been infected were uniformly asymptomatic. The onset of disease is rapid, with fever, severe headache, arthralgia, conjunctivitis, and extreme malaise ( 110). Gastrointestinal symptoms develop within the second to third day followed by hemorrhages at day 5. Bleeding occurs from the mucous membranes, gastrointestinal tract, nasopharynx, and urogenital tract. The fatality rate for Marburg virus infection is approximately 22% of affected patients. The fatality rate for Ebola/Sudan is approximately 60%, and that for Ebola/Zaire is 88% (53, 77, 110). Treatment of the filovirus infections revolves around the administration of large volumes of sterile convalescent plasma and leukocyte-derived interferon (6 1). Infection Control Procedures Since the true reservoir of the filoviruses is still the subject of active investigation, contact with wild mon-

location

Human

Argentina Bolivia Venezuela West Africa Arenavhdae, choriomeningitis

syndrome

Argentine hemorrhagic fever Bolivian hemorrhagic fever Venezuelan hemorrhagic fever Lassa fever only

5 are currently regarded virus of the house mouse

as zoonotics that (Mus musculus),

keys or recently assembled captive monkeys should be considered a risk for potential infection (53, 61, 77, 110). The most effective control measure for the filovirus hemorrhagic diseases is to isolate human cases as soon as possible and to ensure compliance with strict barrier nursing procedures. No vaccine is available at this time for either Marburg or Ebola viruses (53,110).

Arenaviral Hemorrhagic

Fevers

Description, Natural Habitat, and Disease in Animals The etiologic agents of the hemorrhagic fevers of South America (New World) and West Africa (Old World) are several members of the arenavirus family (13,14,77,109). The specific geographic location of each of these viruses is presented in Table 2. The viruses are maintained in nature by infection with specific rodent hosts in which there is a chronic viremia or viruria (77). The arenaviruses are enveloped, single-stranded RNA viruses with several unique properties (77). Four species of RNA can be isolated from intact virions: two are virus specific and code for the nucleocapsid and glycoproteins, and the RNAdependent RNA polymerase, respectively; the other two RNA species are acquired from the host cell and are ribosomal. Genomic viral regulation and selective expression of the virion glycoproteins are considered to be important in the establishment and maintenance of persistent infection both in vitro and in vivo (77). The natural hosts for hemorrhagic fever arenaviruses are various rodent species (Table 2). The viral infections in their natural hosts are persistent and generally regarded to be subclinical (64,77,109). The epidemiology of these viruses in the feral rodent populations is not well described to date but is regarded to have a similar carrier/persistence state as lymphocytic choriomeningitis virus in domestic mice (64). Mode of Transmission to Humans Rodent excreta and saliva are considered to be the primary sources of arenaviral hemorrhagic fever infections in humans in agricultural areas (109). Other sources of human infection are at the nosocomial level with aerosol-contaminated fomites and blood (l3,14, 77). Person-to-person transmission of Lassa fever virus in households is common, a feature that distinguishes Lassa virus from the other pathogenic arenaviruses (109).

CUMITECH

32

Human Infections and Treatment Lassa fever has an incubation period from 7 to 18 days followed by fever, headache, and malaise. Vomiting and diarrhea occur in up to 66% of the patients (109). Mucosal bleeding occurs in up to 20% of all patients. Severe Lassa fever can progress rapidly between th .e 6th and 10th day to respiratory distress, laryngea l edema, shock, and death. Unlike Lassa fever, the Argentine and Bolivian arenaviral fevers do not usually lead to respiratory symptoms (109). Conjunctivitis and erythema of the face, neck, and thorax are hallmarks of these diseases. Patients appear to recover by day 6, but then up to 50% relapse and have neurologic symptoms such as tremors of the hands and tongue, and progress to delirium, oculogyrus, and strabismus (77,109). The most recent arenaviral fever with a known natural host, Guanarito fever, has not been thoroughly investigated to date, but it appears to have some clinical features similar to those of the aforementioned viral diseases. Thrombocytopenia and neutropenia were commonly observed in recently admitted patients. The case fatality rate for this virus may exceed 60% (109).

Diagnosis Diagnosis of the arenaviral hemorrhagic fever viruses requires extreme caution, and the precautions outlined for diagnosis of the filoviruses apply to this group (76). Recommendations involve referral to an appropriate laboratory that has biosafety level 4 containment. These laboratories are listed in the previous section on filoviruses. In the interim period the use of strict barrier nursing procedures (e.g., gown, gloves, and face mask) should be required to minimize nosocomial transmission.

Infection

Control Procedures

Rodent control is the best way to prevent contact between infected animals and humans (13,14,64,77, 109). Rodent trapping in high-risk areas of West Africa and South America has demonstrated a major reduction in the rate of virus transmission and clinical cases in humans. Minimizing contact between rodents and agriculture workers through education programs and hygiene has had a beneficial effect. Control of nosocomial infections requires strict barrier nursing procedures. QF ever

Description, Natural Habitat, and Disease in Animals C. burnetii, the causative agent of Q fever, is a rickettsial organism with two antigenic phases. Phase I organisms are found in nature, and phase II organisms are produced after multiple laboratory passages in eggs or cell culture. Phase II variants are less virulent in laboratory mice and guinea pigs and usually cannot

Diagnosis

of Zoonotic

Infections

15

be isolated from infected animals by standard isolation procedures ( 117). C. burnetii is an obligate intracellular pathogen of eukaryotes and only grows within the acidic compartments of host cells such as in the phagolysosomes. C. burnetii isolates can be grouped into six genomic types, at least four plasmid types, and seven or eight strains that are associated with acute or persistent infections in animals and humans (171). C. burnetii is found worldwide and has an extremely broad host range and exceptional environmental stability. Although C. burnetii has been isolated from arthropods, annelids, many species of birds, domestic and wild mamma ls, and the environment, disease in humans occurs most frequently in areas where domestic animals are prevalent (19). The organism is naturally maintained in a sylvatic cycle involving wild animals and their ectoparasites, but it can also be maintained separately within domestic animal populations (5a, 171). Although the organism has been isolated from almost all species of domestic animals and many species of wild animals, infection in animals is usually inapparent. The mammalian female reproductive system (mammary gland, uterus, and p lacenta) appears to be most susceptible to infection by C. burnetii. Although infrequent, disease due to C. burnetii in domestic animals is recognized primarily in ruminants and usually results in abortion, with concomitant shedding of the organism in large numbers. Even during normal calving or lambing large numbers of rickettsia may be shed in the secretions. Abortions associated with C. burnetii infection in ruminants may occur when the organism is first introduced into a herd before herd immunity is established. Because a herd may contain asymptomatic carriers, with shedding of the organism during parturition, newly introduced animals are at risk for infection and disease. Often the only indication of chronic infection in the mammary gland is detection of the organisms constantly being shed in the milk (171).

Mode of Transmission to Humans The main sources of human infection are domestic animals and their contaminated products (73). The principal mode of transmi .ssion is thro ugh inhalation of contaminated a.erosols. Most cases of Q fever are associated with contact with sheep, goats, and cows during parturition. Q fever is primarily an occupational risk among abattoir workers, farmers, and veterinarians because the most common reservoirs for human infection are domestic ruminants; the main mode of transmission is aerosol, requiring relatively close association with animals (171). A few human cases have been reported from association with parturient cats (89, 91, 105, 106, 137), and one from a dog (26). Although C. burnetii can be shed in milk,

16

Evermann

CUMITECH

et al.

disease associated with ingestion of raw milk containing the organism is infrequent. Regardless, in the late l95Os, the pasteurization temperature for milk was increased to 62.8OC to ensure destruction of C. burnetii (71). Only a few cases of human-to-human transmission have been reported, and most were autopsy room exposures (48,67). Human-to-human transmission by blood or bone marrow transfusion has also been reported (15). Human Infections and Treatment Human infection due to C. burnetii is often asymptomatic, but the disease that occurs is called Q fever. Acute Q fever is characterized by sudden onset of fever and chills, retrobulbar headache, weakness, myalgia, and often profuse sweating. Severity and duration vary. If untreated, the fever may last 9 to 14 days. Pneumonitis may be apparent on radiographs in about half of the patients and may be associated with mild cough and thoracic discomfort. Patients with acute Q fever may also develop nausea, vomiting, and diarrhea. In contrast to other rickettsial diseases, a rash rarely develops in Q fever. Several uncommon manifestations of acute Q fever have been reported and include Guillain-Barre syndrome, encephalitis, optic neuritis, myocarditis, pericarditis, lymphadenopathy, and pancreatitis. Acute Q fever is seldom diagnosed in children under 10 years old, and the disease tends to be more severe in people over 40. The incubation period varies but is usually 2 to 3 weeks (102). Sporadic cases of Q fever often go undiagnosed, obscuring the true incidence of the disease (102). Outbreaks of Q fever are usually occupational and associated with parturient domestic animals, primarily sheep and goats (170). C. burnetii has been isolated from human placenta and breast milk (138). Acute Q fever during pregnancy may be uneventful, with a normal delivery (99, 104). However, there are at least two reports of fetal death associated with Q fever during pregnancy (57, 112) Q fever can also result in chronic disease, primarily affecting the cardiovascular system and causing endocarditis. This is usually reported in individuals with underlying cardiac pathology, such as in individuals with prosthetic cardiac valves (139). Both acute and chronic forms of Q fever hepatitis have been described (103). Treatment with tetracycline or doxycycline for a 2-week period is recommended for acute Q fever. Chronic Q fever requires prolonged treatment with doxycycline and rifampin (176). In Q fever endocarditis, the affected valve often needs to be replaced with a prosthesis before long-term antibiotic therapy can be effective (140). Case fatality rate in untreated Q fever can be as high as 2.4% (1.5). Treated cases rarely

are fatal, except in individuals ditis.

32

who develop endocar-

Diagnosis Diagnosis of acute Q fever is based on clinical symptoms and a fourfold or greater rise in C. burnetiispecific antibody against phase I and phase II antigens in the microagglutination, complement fixation, or immunofluorescence test or the ELISA (162, 173). Phases I titers may be either equal to or greater than phase II titers. IgG and IgA titers to phase I antigen are generally greater in chronic Q fever (140). Enhanced phase I titers of IgG and IgA along with compatible clinical findings are diagnostic for Q fever endocarditis (134). The agent can be isolated from blood during the febrile period and sometimes from sputum and urine in humans. Of the rickettsial agents, however, C. burnetii probably presents the greatest risk for laboratory infection (32). The estimated human infectious dose by inhalation is only 10 organisms (168). Few laboratories are equipped with the biosafety level 3 facilities required to permit safe isolation (32). Thus, serologic tests are preferred. Infection Control Procedures It is not practical or feasible to eliminate the animal reservoirs of C. burnetii because of the broad host range, size of the animal populations infected, and the various cycles of domestic and wild animal transmission (73). Recommendations for reducing human risk in research facilities that use ruminants have been established. These include ongoing serologic surveillance of the animals and isolation or culling of seropositive animals where possible, avoiding the use of pregnant animals, and worker education along with immunologic screening, medical surveillance, and possible vaccination (20, 149). Outside of research facilities there is little incentive to prevent infection in animals because infection is usually inapparent. Vaccination of animals may reduce rickettsial shedding but not eliminate it (l2,21). A formalin-inactivated phase I whole-cell vaccine has been developed for use in humans (130). This vaccine is not commercially available in the United States but can be obtained under an investigational new drug protocol (171). Because va ccination with the ph .ase I whole-cell preparation frequently causes severe local reactions i.n subjects wi th preexisti ng immunity, individuals should first be screened to demonstrate a negative skin test (171). Subunit vaccines for human use are under investigation (58,107,170).

Introduction

and Sample Preparation

Both wild and domestic animals can be infected with a number of different parasites. In some cases, various

CUMITECH

32

Diagnosis

protozoan and helminth parasites of animals can be transmitted to humans. These parasites infect humans via the oral route, and the majority of the infections are transmitted in food or water. Many of these infections are rare and cause no problems; however, some are more common and have public health significance. Although many of these infections have been largely eliminated in most developed countries, continued increase in world trade related to food commodities and increased travel could lead to a higher prevalence of some of these diseases. To minimize increased risk of new or expanded parasitic zoonoses, it is important that health care personnel be aware of such potential infections. This Cumitech will review only those agents that are transmitted directly or indirectly to humans through animals, not by insect vectors. These parasites can generally be grouped into two categories: 1 . Parasites that are present in the tissues of food animals, and their life cycle stages can be infective to humans. Transmission depends on ingestion of raw or poorly cooked food. 2 . Parasites that are found in the environment (soil or water), and the infective stages can be transmitted in food. Transmission depends on ingestion of improperly prepared food or food that has been contaminated after processing or preparation. Many of these parasites have complex life cycles, and specific terms describe different stages in these cycles. The “definitive” host is the animal in which the parasite reaches maturity and often undergoes sexual reproduction. The ‘(intermediate” host is a required host in the life cycle in which larval development takes place; this stage must occur before the parasite is infective for the definitive host or secondary intermediate hosts. Asexual reproduction may occur in these hosts. Table

3.

Preservatives

used

with

diagnostic

parasitology

Preservative 5 or 10% Formalin . . .. . . . . . . . . . . . . . . . . . . .. . . . . ..*........................................... 5 or 10% Buffered formalin . . . . . . .. . . . . . . . . . . . . . ...*...............................*.. MIF ..,,.....,..,....~..,,.~......~.~................................................................ SAF . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . ..*............................................*............... PVAd .~,.........*........,........*.........................................*...................... PCA-modified” . .. . . . . . . . . . . . . . . .. .. . . . . . . . . . . . ..*.........*........................*.......... PVA-modif ied’ . . .. . . . . . . ..*.............*..........................*.................*......... Single vial systemsg . . . . .. .. . . . . . . . . . . . . . . . .. .. . . . . . . . . . . . . . . . . . . . . ..*..................... Schaudinn’s (without PVA)d . . . . . . . . . . . .. .. . . . . . . . . . . . . . . . . . . . . . . . .. ...*...............

of Zoonotic

Infections

17

Other terms are commonly used to describe the morphologic stages found in some of the protozoan parasites. The “trophozoite” stage of a protozoan parasite is the active, feeding form, in contrast to the “Cyst,” which is the resistant stage found in the environment that is normally transmitted from one host to another. The coccidia are transmitted via the oocyst and the microsporidia via the spore, both of which are the resistant life cycle stages in the environment. Helminth infections are transmitted via the ingestion of infective eggs or the penetration of skin and mucous membrane by infective larvae. Diagnosis of zoonotic parasitic infections is usually accomplished through either laboratory examination of clinical specimens or immunologic tests to identify parasite antigen or specific antibody to the parasite (59, 76, 101). Th e d ecision to use a particular collection method or methods should be based on a thorough understanding of the advantages and disadvantages of each procedure (Table 3). One of the most important aspects of specimen collection is that the final laboratory results will be based on parasite recovery. Therefore, identification will depend on the initial handling and preservation of the organisms. Unless the appropriate specimens are properly collected and processed, the infections may not be detected. Protozoa Microsporidiosis Descrifjtion, mode of transmission, and prevention. Microsporidiosis, an important emerging opportunistic infection in human immunodeficiency virus (HIV)infected patients, has also been found in immunocompetent individuals. The microsporidia are obligate intracellular parasites that have been recognized in a variety of animals. Organisms found in humans are

methods

(stool

specimens) Permanent

stained

smeara

Modified acid-fast stair?, modified trichrome stainC Modified acid-fast stain, modified trichrome stain Polychrome IV stain Iron-hematoxylin, modified acid-fast stain, modified trichrome Trichrome or iron hematoxylin stain Trichrome or iron hematoxylin stain Trichrome or iron hematoxylin stain Trichrome or iron hematoxylin stain Trichrome or iron hematoxylin stain

‘All methods listed can be performed on specimens preserved in the fixative(s) listed in the same row. ’ Modified acid-fast stains are used for the identification of Ctyptosporidium spp. c Modified trichrome stains are used for the identification of microsporidia. ‘These two fixatives use the mercuric chloride base in the Schaudinn’s fluid; this formulation is still considered to be the “gold standard” which all other fixatives are evaluated (organism morphology after permanent staining). Additional fixatives prepared with non-mercuric based compounds are continuing to be developed and tested. eThis modification uses a copper sulfate base rather than mercuric chloride. ‘This modification uses a zinc base rather than mercuric chloride and apparently works well with trichrome and iron-hematoxylin stains. g These modifications use a combination of ingredients (including zinc) but are prepared from proprietary formulas.

stain

against chloride-

18

Evermann

CUMITECH

et al.

32

Humans rarious

hod y sitesy

Ingestion or inhalation of spores (person to person) (animal sources)

Spores in stool, urine, etc.

ISpores

FIGURE

survive b in food, Hz0 1.

Life cycle

small, ranging from 1.5 to 2 pm. One characteristic of the life cycle of microsporidia is the presence of spores containing a polar tubule, which is an extrusion mechanism for injecting the infective spore contents into host cells (Fig. 1). To date, seven genera have been recognized in humans: Encephalitoxoon, Nosema, Tracbipleistophora, EnVittaforma, Pleistophora, terocytozoon, and Microsporidium, a catch-all genus for those organisms not yet classified (59, 123). Infection occurs with the introduction of infective sporoplasm through the polar tubule into the host cell. The microsporidia multiply extensively within the host cell cytoplasm; the life cycle includes repeated divisions by binary fission (merogony) or multiple fission (schizogony) and spore production (sporogony). During sporogony a thick spore wall is formed, thus providing environmental protection for this infectious stage of the parasite. The spores of Enterocytozoon bieneusi are released into the intestinal lumen and are passed in the stool. These spores are resistant to environmental conditions and can be ingested by other hosts. There is also evidence for inhalation of spores. The sources of human infections are not yet well defined, nor are all the reservoir hosts. Possibilities include human-to-human transmission and animalto-human transmission. Primary infection can occur by inhalation or ingestion of spores from environmental sources or by zoonotic transmission. The presence of infective spores in human clinical specimens suggests that precautions when handling body fluids and personal hygiene measures such as hand washings may be important in preventing primary infections in the health care setting. However, comprehensive guidelines for disease prevention will require more definitive information regarding sources of infection and modes of transmission. Human infections and treatment. Both Encephalitozoon cuniculi and E. hellem have been isolated from human infections, the first species from the central

of the microsporidia.

nervous system and the second from the eye. Currently, there are at least three E. cuniculi strains that may become more important in human infections. Several eye infections with E. hellem in AIDS patients have been reported. Nosema connori has been identified in human tissues, with spores that are oval and measuring approximately 2 by 4 km. The single human case occurred in a 4-month-old infant with combined immunodeficiency disease with a disseminated, fatal infection. Nosema corneum has been reclassified as Vittaforma corneae. Microsporidia of the genus Pleistophora have rarely been identified in humans. However, when they were found, atrophic and degenerating muscle fibers were full of spores, which were seen in clusters. Another isolate causing severe progressive myositis, and associated with fever and weight loss in a patient with AIDS, was reported in late 1996 and has been named Trachipleistophora hominis. A number of cases of infection with E. bieneusi have been reported in AIDS patients. Chronic intractable diarrhea, fever, malaise, and weight loss are symptoms of E. bieneusi infections. These symptoms are similar to those seen with cryptosporidiosis or isosporiasis. These patients have already been diagnosed with AIDS and each day tend to have four to eight watery, nonbloody stools that may be accompanied by nausea and anorexia. Encephalitozoon intestinalis (formerly Septata intestinalis) infects primarily small-intestinal enterocytes, but infection does not remain confined to epithelial cells. E. intestinalis is also found in lamina propria macrophages, fibroblasts, and endothelial cells. Dissemination to kidneys, lower airways, and biliary tract appears to occur via infected macrophages. Over the past few years, confirmatory evidence indicates a complete parasitological cure is possible with albendazole. Although albendazole has been

CUMITECH

Diagnosis

32

of Zoonotic

Infections

19

Humans

Ingestion of undercooked pork containing encysted l&e larvae carried via bloodstreom to muscles (penetrate and encyst)

Lorvoe liberoted when cyst digested

l Femole worms penetrate

mature and mote in upper intestine

mucoso

ond liberate lorvoe FIGURE

2.

Life cycle

of Trichinella

/

Parasites

spiralis.

thought not to be effective for E. bieneusi infections, there are some reports of infections resolving in noncompromised patients after treatment with albendazole. However, the immune system may play a role in control of this organism within the intestine. Diagnosis. Modified trichrome stains are recommended in which the chromotrope 2R component added to the stain is 10 times the concentration normally used in the routine trichrome stain for stool. Stool preparations must be very thin, the staining time is 90 min, and the slide must be examined at 1,000 X (or lhigher) magnification. If this stain is used for the identification of microsporidia in stool, positive control material should be available for comparison. There are several newer methods, such as a Wheatley’s trichrome using heat, a combination acid-fastchromotrope stain, and a combination Gram-chromotrope technique. Another approach involves the use of chemofluorescent agents (optical brightening agents) such as Calcofluor, Fungi-Fluor, or Uvitex 2B. The newest approach uses antisera in an indirect fluorescent antibody procedure. Commercial products are in various stagesof development and clinical testing and should result in additional, more sensitive methods. Current recommendations also suggestthat multiple diagnostic methods may be necessary to diagnose microsporidiosis, particularly with stool. Commercial PCR products are not yet available.

Nematodes Trichinella spiralis Description, mode of trdnsmission, and prevention. This particular nematode infection has a cosmopolitan distribution but is more important in the United States and Europe than in the tropics or the Orient. Human infection occurs from the ingestion of raw or poorly cooked pork, bear, walrus, or horse meat or meat from other mammals (carnivores and omnivores) containing viable, infective larvae (Fig. 2) (59, 101). The tissue is then digested in the stomach. The

Reprinted

from

reference

58a with

permission.

excysted larvae invade the intestinal mucosa, develop through four larval stages, mature, and mate by the second day. By the sixth day of infection, the female worms begin to deposit motile larvae, which are carried by the intestinal lymphatic system or mesenteric venules to the body tissues,primarily striated muscle. Deposition of larvae continues for approximately 4 weeks, with each female producing up to 1,500 larvae in the nonimmune host. The very active muscles, including the diaphragm; muscles of the larynx, tongue, jaws, neck, and ribs; the biceps; gastrocnemius; and others-which have the greatest blood supply- are invaded. The cyst wall results from the host’s immune response to the presence of-the larvae, and the encysted larvae may remain viable for many years, although calcification can occur within lessthan a year. As few as 5 larvae per g of body muscle can cause death, although 1,000 larvae per g have been recovered from individuals who died from causesother than trichinosis. Several cycles maintain the infection: (i) pig to pig, (ii) rat to rat, and (iii) sylvatic (among carnivores and omnivores). Feeding pigs uncooked garbage containing infected meat scraps probably accounts for most infections of pigs in the United States. Investigation of T. spiralis transmission on a pig farm indicated that even in the absence of a known source of infected meat, the rat population maintained the infection, probably through cannibalism (98). Consequently, to reduce transmission of T. spiralis between rats and swine, rat populations in an agricultural ecosystem must be controlled. It is also important to limit access to the farmyard by wild and feral animals. Preventive measuresfor pork containing temperatezone strains include refrigeration at 5’F (- 15OC) for not lessthan 20 days, at -lOoF (-23°C) for 10 days, or at -2O’F (-29OC) for 6 days or deep freezing (-35’F [-37”C]). Smoking, salting, and drying are not effective. On the basisof a number of studies, the current recommendation statesthat “all parts of pork

20

Evermann

CUMITECH

et al.

muscle tissue must be heated to a temperature not lower than 137’F (58.3”C)” (59). Reduction in the number of cases is due primarily to regulations requiring heat treatment of garbage and low-temperature storage of the meat. Human infections and treatment. Pathology is usually based on the original number of ingested cysts. Symptoms that may develop within the first 24 h include diarrhea, nausea, abdominal cramps, and general malaise, all of which may suggest food poisoning, particularly if several people are involved. During muscle invasion, there may be fever, facial (particularly periorbital) edema, and muscle pain, swelling, and weakness. The extraocular muscles are usually the first to be involved, followed by the muscles of the jaw and neck, limb flexors, and back. The most severe symptom is myocarditis, which usually develops after the third week; death may occur between the fourth and eighth weeks. Other severe symptoms, which can occur at the same time, may involve the central nervous system. Although Trichinella encephalitis is rare, it is life threatening. Peripheral eosinophilia of at least 20%, often over 50%, and possibly up to 90% is present during the muscle invasion phase of the infection. An increased eosinophilia (increase in the number of eosinophilic granulocytes in the circulating blood) is normally associated with certain parasitic infections, particularly those in which there is close contact with host tissues and migrating larval or adult helminths. T. spiralis is an excellent example of a parasitic infection where the number of eosinophils in the peripheral blood is increased. This type of leukocyte is evidence of an allergic response to some foreign antigen, and it can be seen and quantitated on a routine peripheral blood smear examination. Fever can also be present at this time and persist for several days to weeks, depending on the intensity of the infection. However, once the larvae begin to encapsulate, patient symptoms subside, and eventually the cyst wall and larvae calcify. There is no specific recommended therapy for trichinosis. Thiabendazole has been used with limited success when given during very specific time frames. Mebendazole has also been tried on a limited basis. During muscle invasion by the larvae, corticosteroids may decrease the severity of the disease. Diagnosis. Trichinosis should be considered in any patient with periorbital edema, fever, myositis, and eosinophilia, regardless of whether a complete history of consumption of raw or poorly cooked pork is available. If present, subconjunctival and subungual splinter hemorrhages also support such a presumptive diagnosis. If the meat consumption history is incomplete, food poisoning, intestinal flu, or typhoid may be suspected. It is very rare to recover adult worms or

32

larvae from stool or other body fluids (blood, cerebrospinal fluid, etc.) if the patient has diarrhea. Muscle biopsy (gastrocnemius, deltoid, and biceps) specimens may be examined by compressing the tissue between two slides and checking the preparation under low power of the microscope (10 X objective). However, this method does not become positive until 2 to 3 weeks after the onset of the illness. Muscle specimens or samples of the suspect meat can also be examined with an artificial digestion technique to release the larvae. Serologic tests are also helpful, the standard assays being ELISA and the bentonite flocculation tests. Angiostrongylus cantonensis Description, mode of transmission,

and prevention.

This infection has been recognized in the Pacific areas for many years, and is endemic in Thailand, Tahiti, and Taiwan. Sporadic cases have also been reported from Central America and Cuba, and one case from the United States. Apparently, many gastropods in New Orleans, La., are competent hosts for A. cantonensis. Also, infected rats and primates have been identified at the Audubon Zoo, indicating a reservoir of infection is present in New Orleans. The infection is associated with eosinophilic meningitis and sometimes eye involvement. Human infection begins with the accidental ingestion of infective larvae in several species of slugs, snails, or land planarians (11,22,59). Larvae migrate to the brain gray matter, where they mature in approximately 4 weeks. Yo ung adult worms then migrate to the pulmonary arteries and within 2 weeks begin egg deposition (up to 15,OOO/day). In the natural li .fe cycle, infective larvae have also been found in land crabs, coconut crabs, and freshwater prawns, which in the Pacific islands are often consumed raw (Fig. 3). The worms are thin and delicate, measuring 17 to 25 mm long by 0.26 to 0.36 mm wide. The young adult worms within the brain tissue are approximately 2 mm long. The lack of host specificity, natural mobility of rats, and expansion of the geographic range of the large African land snail have all contributed to the spread of this infection throughout the tropical and subtropical areas of the world. It is often difficult to identify the specific source of human infections; however, awareness of the various possible hosts may decrease the number of infections. No overall control measures have been recommended. Human disease and treatment. The incubation period is normally about 20 days, and the main symptom is severe headache. Other symptoms include convulsions, weakness of the limbs, paresthesia, vomiting, facial paralysis, neck stiffness, and fever. The spinal fluid usually contains white blood cells with many

CUMITECH

32

Diagnosis

of Zoonotic

Infections

21

Rats Adult worms in pulmonary arterie Larvae mature in pulmonary arteries I (1) Larvae reach central nervous system (CNS)

Eggs

ANGIOSTRONGYLUS CANTONENSIS (Eosinophilic Meningitis)

Slugs, snails eaten/ by rats or HUMANS \ Bowel

carried

to: \ Lungs 1 Trachea ‘I Swallowed r Larvae in stool b Larvae invade slugs, snails

wall

ANGIOSTRONGYLUS COSTARICENSIS (Abdominal anglostrongylosis) Cycle FIGURE

3.

Life cycle

of Angiostrongylus

cantonensis

end.s

and A. costaricensis.

eosinophils. There is often a peripheral eosinophilia with moderate leukocytosis. Eye involvement is characterized by visual impairment, pain, possible retinal hemorrhage, and retinal detachment. If the worm is found in the eye, surgical removal of the worm is usually recommended. The patient from New Orleans was an U-year-old boy who presented with myalgia, headache, low grade fever, and vomiting. He had no travel history but admitted that, on a dare, he had eaten a raw snail from the street a few weeks earlier. Most patients, including the one from New Orleans, recover uneventfully and do not require hospitalization. Symptoms gradually disappear, with meningeal problems resolving first, followed by visual abnormalities and finally paresthesia. Anthelmintic agents are usually not used, although both mebendazole and thiabendazole have been tried. Mebendazole is currently the drug of choice. Diagnosis. A presumptive diagnosis can be made in areas where infections are endemic on the basis of patient symptoms of severe headache, meningitis, or meningoencephalitis, with fever and ocular involvement. A peripheral eosinophilia and eosinophils in the spinal fluid also are highly suggestive of this infection. Lesions also can be seen in the brain by computed tomography scan. Often larvae or young adult worms can be recovered in the spinal fluid. ELISA can also support confirmation of A. cantonensis infection.

Reprinted

from

reference

59 with

Angiostrongylus costaricensis Description, mode of transmission,

permission.

and prevention.

The cotton rat, the black rat, and a number of other rodents have been found to harbor the adult worms, while various slugs harbor the larvae. Human infections are most common in Costa Rica but have been reported in other areas of Mexico and Central and South America. The life cycle is similar to that of A. cantonensis, with human infection being initiated by accidental ingestion of the appropriate slug, frequently on contaminated salad vegetables (Fig. 3). This infection is called abdominal angiostrongylosis, and the worms cause inflammatory lesions of the bowel wall (l&22, 59). Most of the infections reported from Costa Rica have been in children. Prevention involves rodent control to break the parasite’s normal life cycle. Human disease and treatment. Often the appendix is involved; however, the worms can also be found in the terminal ileus, cecum, ascending colon, regional lymph nodes, and mesenteric arteries. There may be inflammation, thrombosis, and regional necrosis, with granulomas and areas of eosinophilic infiltrates around eggs and larvae in various stages of development. The most common symptoms are pain and tenderness, with a palpable mass in the lower right quadrant, along with fever and possibly vomiting and diarrhea. Occasionally the worms may be in the liver, and symptoms may mimic those of visceral larval

22

Evermann

CUMITECH

et al.

32

Cats, Dogs //Reenter

Minatsu::2:

L&

feces

stomach

f Visceral larva migrans

\ Water \ Ingested by cyclops

GNATHOSTOMA SPINIGERUM

1

ingested by fish, eels, frogs snakes, birds k Larvae encyst in muscle CYCLOPS

Larvae

penetrate k

Cats, Dogs, HUMANS Ingestion of raw flesh (fish, birds, etc.) containing larvae

Cycle ends FIGURE

4.

Life

cycle

of Gnathostoma

spinigerum.

migrans. A leukocytosis is present with an eosinophilia of up to 80%. Several drugs have been used for treatment; the drug of choice is thiabendazole, with another option being mebendazole. Diagnosis. Eggs or larvae may be seen in tissue sections, with most specimens being diagnosed on microscopic examination. Without histologic sections, the diagnosis is made on clinical grounds. Gnathostoma spinigerum Description, mode of transmission, and prevention. Although many Gnathostoma species have been mentioned in the literature, only G. spinigerum is considered to be medically important (11, 22,45, 59, 101, 124). This parasite is normally found in dogs and cats, and Thailand has the most infections, both in humans and in reservoir hosts. Areas of endemicity include China, the Philippines, and other areas in the Far East. However, the first record of a confirmed case of G. doloresi was reported from Japan. Although the entire life cycle is not fully understood, the patient reported eating raw brook trout about 2 months before the onset of the creeping eruption. A recent case report from Japan describes colonic ileus due to nodular lesions caused by G. doloresi. Human infections are acquired by the ingestion of raw or poorly cooked or pickled freshwater fish, chicken or other birds, frogs, or snakes (Fig. 4). There is also speculation that human infection can occur from the ingestion of copepods containing the advanced third-stage larvae or actual skin penetration of

Reprinted

from

reference

59 with

permission.

larvae from handling infected meat. In the normal host, the ingested larvae mature in the stomach wall in about 6 months. Eggs are then extruded from the stomach lesions and are passed out in the feces, where they hatch and embryonate in water. The larvae are then ingested by copepods, which in turn are ingested by a number of freshwater fish, frogs, snakes, or birds. The adult worms, which are found in the stomach tumors, measure from 25 to 54 mm (females) and 11 to 2.5 mm (males). The anterior half of the worm is covered with leaf-like spines. Most infections are probably caused by the ingestion of raw or poorly cooked fish, domestic ducks, and chickens. The larvae do not survive cooking and can also be killed by immersion in strong vinegar for at least 5 h. Unfortunately, soaking in lime juice or storage at 4OC for a month does not kill the larvae. Human disease and treatment. In the human host, the larvae migrate throughout the body. Several days after ingestion of the larvae, penetration of the intestinal wall may lead to epigastric pain, vomiting, and anorexia. These symptoms subside as the larvae begin to migrate through the tissues in deep cutaneous or subcutaneous tunnels. Evidence of this migration appears either as lesions similar to those found with cutaneous larval migrans, or more commonly, as migratory swellings with inflammation, redness, and pain. This swelling is hard and nonpitting and may last for several weeks. After it disappears, it may reappear in a location not far from the first swelling,

CUMITECH

32

Diagnosis

Whale,

Seal, Dolphin,

of Zoonotic

Infections

23

Porpoise

Adult worms In Intestine Eggs In feces

Eggs hatch In water

ANISAKIS PHOCANEMA CONTRACAECUM

Larvae Ingested by crustaceans Crustaceans Ingested by fish, squid (larvae In body cavity or muscles) I or ‘I HUMANS 7 Ingestion of raw or poorly cooked fish, squid. Focal ulcerations stomach or bowel - larvae may be expelled by coughing 7 Cycle ends FIGURE

5.

Life cycle

of Anisakis,

Phocanema,

and

Contracaecum

which can be on the upper extremity, shoulder, neck, thorax, face, scalp, abdominal wall, thigh, or foot. The lesions may be painless, or they may be painful and pruritic. These swellings probably result from the host’s allergic response to the presence of the worms, and an eosinophilia of 35 to 80% is reported in patients with cutaneous involvement. Newer serologic methods may also be helpful in diagnosis. More serious symptoms can occur if the eye or central nervous system is involved. The larval migration occurs along a peripheral nerve, into the spinal cord, and then into the brain. Symptoms may include pain, paralysis, seizures, coma, and death. The spinal fluid may be xanthochromatic or bloody. Ocular invasion probably occurs via the optic nerve, although penetration through the sclera may be possible. The only effective therapy is surgical incision of the lesion and removal of the worm. Albendazole has also been recommended as an adjunct to surgical removal. Worm removal from the eye may also prevent central nervous system invasion. The prognosis is usually good unless the “central nervous system is involved. Diagnosis. Patient symptoms may also include sparganosis, cutaneous paragonimiasis, cutaneous larval migrans, and myiasis in the differential diagnosis. Spinal fluid that is bloody or xanthochromic and contains many eosinophils may be suggestive of infection with A. cantonensis. A definitive diagnosis depends on worm recovery and identification.

spp.

Reprinted

from

reference

59 with

In

permission.

Anisakis spp., Phocanema spp., and Contracaecum spp. (Larval Nematodes Acquired from Saltwater Fish) Description, mode of transmission, and prevention. Anisakiasis was first recognized and reported from the Netherlands. Since this infection was reported from Japan in 1965, hundreds of Japanese cases have been documented, as well as several from the United States. It is now well recognized that human infection can occur from the ingestion of raw or poorly cooked marine fish (59, 101). Human infection is acquired by the ingestion of raw, pickled, salted, or smoked saltwater fish (Fig. 5). The larvae often penetrate into the walls of the digestive tract (frequently the stomach), where they become embedded in eosinophilic granulomas. Occasionally the throat may be involved. These large larvae (third stage) measure 1 to 3 or more cm long by 1 mm wide. In parts of the world where anisakiasis has been reported, raw, pickled, salted, or smoked marine fish should be avoided. Total disease prevention could be accomplished by thorough cooking of all saltwater fihs . Human disease and treatment. There may be nausea or vomiting, often within 24 h after ingestion of raw marine fish. Depending on the location of the larvae, infections can mimic gastric or duodenal ulcer, carcinoma, appendicitis, or other conditions requiring surgery. There is usually a low-grade eosinophilia (10%

24

Evermann

CUMITECH

et al.

or less), and the stool is positive for occult blood. Pulmonary anisakiasis has also been reported. Worms have been recovered or seen after surgery for intestinal obstruction, in eosinophilic granulomas, from a portion of resected small intestine, during gastroscopic examination, in vomitus, or in histologic sections. Many patients will cough up the larvae, and the infection will be aborted at that point. The eosinophilic granuloma in the gastrointestinal tract often mimics a malignancy, and without surgery and examination of the tissues, a final diagnosis cannot be confirmed. There is no recommended therapy other than removal of the larvae, often through surgery. Diagnosis. A presumptive diagnosis can be made on the basis of the patient’s food history. Definitive identification is based on larval recovery or histologic examination of infected tissue. Miscellaneous. Some trematodes that infect animals may also be capable of infecting humans. For example, humans can become infected with the pig Ascaris species, Ascaris sawn. Studies also indicate that worms indistinguishable from A. lumbricoides have been reported in chimpanzees, gorillas, orangutans, gibbons, and various macaques. Experimental animal studies also show that chimpanzees inoculated with A. lumbricoides eggs passed fertile eggs in the feces for several months (11). Although pigs are susceptible to infection with human Ascaris, none of the primates or any other susceptible animal except the pig is a significant reservoir of infection. Although not confirmed, it is thought that the Trichuris species in pigs may be the same as that found in humans. Also, heavy infections with what is presumed to be Trichuris trichiura produce disease in chimpanzees (11). Detailed information on Ascaris and Trichuris ecology, infections, and diagnosis can be found in reference 59. Intestinal Cestodes Adult cestodes, or tapeworms, live attached to the mucosa in the small intestine and absorb food from the host’s intestine. The attachment organ is called the scolex, to which is attached a chain of segments or proglottids called the strobila. Each proglottid contains a male and female reproductive system. The proglottids are classified as immature, mature, or gravid (the latter are found at the end of the strobila and contain the fully developed uterus full of eggs). The uterine structure in the gravid proglottids is often used as the main criterion for identification. The eggs and/or scolex can also be used to identify a cestode to the species level. Cestodes have complex life cycles that usually involve both the intermediate and definitive hosts. In some infections, humans serve as only the definitive hosts, with the adult worm in the intestine (Diphyl-

32

lobothrium latum, Taenia saginata, Hymenolepis diminuta, and Dipylidium caninum). In other cases,

humans can also serve as both the definitive intermediate hosts (T. solium and H. nana).

and

Diphyllobothrium latum Description, mode of transmission, and prevention. The distribution of D. latum is worldwide. Infection

with the adult ‘worm is acquired by the ingestion of raw, poorly cooked, or pickled freshwater fish (pike, perch, lawyer, salmon, trout, white fish, grayling, ruff, burbot, etc.) containing the encysted plerocercoid larvae (Fig. 6). After ingestion, the worm matures, and egg production begins after about 5 or 6 weeks. The adult worm may reach a length of 10 m or more (59, 101).

The scolex of D. latum is elongate and spoon shaped, and has two long sucking grooves: on .e on the dorsal surface and the other on the ventral surface. The mature and gravid proglottids are wid .er than long, with the m.ain reproductive structures (mainly the uterus) located in the center of the gravid proglottid. This configuration of the uterine structure has been called a rosette. Identification to the species level is usually based on this typical morphology of the gravid proglottids. Both eggs and proglottids may be found in the stool. Often a partial chain of proglottids may be passed (a few inches to several feet). The eggs are broadly oval and operculated. After developing for 2 weeks in fresh water, the eggs hatch and the ciliated coracidium larvae are ingested by the first intermediate host, the copepod. The copepods, containing the second larval stage (procercoid), are then ingested by fish, which may be ingested by larger fish. In this situation, the final fish intermediate host may contain many plerocercoid larvae, which initiate the infection with the adult worm when ingested by humans. It is possible to acquire the infection from the ingestion of infected raw freshwater fish that has been shipped under refrigeration to areas where the infection is not endemic. Preventive measures include thorough cooking of all freshwater fish and freezing for 24 to 48 h at - 18OC. Groups who tend to eat raw or insufficiently cooked fish include the Russians, Finns, and Scandinavians. Raw fish marinated in lime juice (ceviche) is also a source of infection (D. pacificurn) in Latin America. Since the domestic dog can serve as a reservoir host, dogs that are infected should be periodically treated. Human disease and treatment. Symptoms in the Patient depend on the number of worms present, the amounts and types of by-products produced by the worm, th .e patient’s reaction to such by-products, and the absorption of various metabolites by the worms. There may be occasional intestinal obstruction, diarrhea, abdominal pain, or anemia. If the worm is

CUMITECH

Diagnosis of Zoonotic

32

Infections

25

Humans

Adult worms in intestine Humans

ingest

Eggs/proglottids in feces

fish

I

J Eggs hatch in water

Fish ingests

COP~P<

copepod

ingests FIGURE

6.

Life cycle

of Diphyllobothrium


larva

latum.

Reprinted

from

reference

58a with

permission.

cercosis infections with T. solium (larvae) are relatively common in certain parts of the world but rare within the United States. This extraintestinal form of the infection is far more serious than the presence of the adult worm in the intestine. Infection with the adult worm occurs through ingestion of raw or poorly cooked pork containing encysted T. solium larvae (Fig. 7). The larva is digested out of the meat in the stomach, and the tapeworm head evaginates in the upper small intestine, attaches to the intestinal mucosa, and grows to the adult worm within 5 to 12 weeks. Usually a single worm is present, reaches a length of 2 to 7 m, and may survive 25 years or more. The scolex has four large suckers with a rounded rostellum containing a double row of hooks. The neck region is short and about half the width of the scolex. Identification to the species level is usually based on the number of lateral uterine branches in the gravid proglottid. The main lateral branches should be counted where they come off the main central stem. Only one side is counted, and there are between 7 and 13 branches, with an average of 9. The terminal gravid proglottids break off from the

attached at the jejunum, there may be a vitamin B,, deficiency, which resembles pernicious anemia and which develops in a very small percentage of persons harboring the tapeworm. The clinical picture is seen most frequently in Finland, where individuals tend to have a genetic predisposition to pernicious anemia. In patients without this genetic predisposition, symptoms of a D. latum infection may be absent or minimal, with a slight leukocytosis with eosinophilia. The use of both praziquantel and niclosamide has been recommended for therapy. Diagulosis. Diagnosis is usually based on the recovery and identification of the characteristic eggs or proglottids. The eggs are unembryonated at the time they are passed in the stool. Proglottids are often passed in chains (a few inches to several feet), and this is a clue to D. latum. The overall proglottid morphology with the rosette uterine structure also facilitates identification. Taenia solium Description, mode of transmission, and prevention. T. solium is found in many parts of the world and is

considered an important human parasite where raw or poorly cooked pork is eaten (11, 59, 101). CystiHumans Adult

worms

in intestine

Taenia saginutu Ingested in uncooked beef, pork

Tueniu

\ Cysticerci in muscle

FIGURE

7.

-

Life cycle

Taenia solium (cysticercosis)

solium

t

Eggs/proglottids in feces Eggs A ingested by cattle, pigs of Taenia

solium

and

T. saginata.

Reprinted

Cysticerci in muscle, brain, etc.

Eggs ingested by humans from

reference

58a with

permission.

26

Evermann

et al.

main strobila and are passed out in the stool or actually migrate out of the bowel. In some cases, three or four attached proglottids may pass out in the stool. The eggs are round or slightly oval (31 to 43 km), have a thick, striated shell, and contain a six-hooked embryo or oncosphere. These eggs may remain viable in the soil for weeks. On ingestion by hogs or humans, the eggs hatch in the duodenum or jejunum after exposure to gastric juice in the stomach. The released oncospheres penetrate the intestinal wall, are carried via the mesenteric venules throughout the body, and are filtered out in the subcutaneous and intramuscular tissues, the eye, the brain, and other body sites. This cysticercus is an ovoid, milky white bladder with the head invaginated into the bladder. The bladder worms measure 5 mm long by 8 to 10 mm wide. The host generally produces a fibrous capsule around the bladders, unless they are located in the brain, particularly the ventricles. Although other animals can occasionally harbor the cysticercus stage, poorly cooked or raw pork is the only source of human infection for the development of the adult worm. Human infection and cysticerci can involve thousands of organisms obtained from various sources: ingestion of T. solium eggs in contaminated food or water; self-infection from the presence of the adult worm in the intestine. Internal autoinfection is also possible, in which the eggs come in contact with the stomach acid, possibly allowing hatching and penetration of the larvae into the tissues. Prevention involves awareness of the infection route and the use of good sanitary and personal hygiene measures. The ingestion of vegetables fertilized by sewage should also be avoided. Adequate requirements for human sewage disposal should be followed. One of the most important means of prevention is the adequate cooking of pork and pork products; thorough cooking at 65OC will kill the cysticerci. However, salting and pickling of the meat are usually not effective. Human disease and treatment. Adult worm. The presence of the adult worm may cause slight irritation at the site of attachment or vague abdominal symptoms (hunger pains, indigestion, diarrhea, and/or constipation). There may be a low-grade eosinophilia, usually under 15 % . Cysticercosis. The larval forms of T. solium (cysticerci) have been recovered from all areas of the body, and symptoms depend on the particular body site involved. Cysticerci in the brain represent the most frequent parasitic infection of the human nervous system. Neurocysticercosis usually affects males and females of all ages, with a peak incidence between 30 and 50 years of age. When the larvae are found in the brain, symptoms can result from larval invasion of the brain tissue and/or death of the organism, which

CUMITECH

32

stimulates tissue reactions around the larvae. It has been recommended that in every case of epilepsy occurring in a patient with no family history of fits and no previous history of fits in childhood, the probability of cysticercosis should be entertained. Other symptoms include abnormal behavior, transient paresis, intermittent obstructive hydrocephalus, disequilibrium, meningoencephalitis, and visual problems. Cysticerci in the eye can be found in various areas, including in the eyelid and under the conjunctiva. The larvae are unencapsulated when found in the vitreous or anterior chamber and will actively change shape, casting shadows in front of the retina. Unless the organism is removed, permanent eye damage may occur, particularly if the parasite dies, thus stimulating an intense inflammatory reaction. Cysticercus (racernose type). The racemose, or proliferating, form of the cysticercus is composed of several bladders that are connected and are often found in the brain, particularly the fourth ventricle and subarachnoid space. No scolices are found within these bladders, and the growth may resemble that of a metastatic tumor. Other larval cestodes may also have a racemose growth pattern, and it may be very difficult to differentiate a T. solium racemose cysticercus from other types by histology. The prognosis for such infections is very poor (22). The use of praziquantel or niclosamide has been recommended for the adult worm. Since there is always the possibility of cysticercosis via autoinfection, patients should be treated as soon as diagnosed. In cases of cysticercosis, surgical removal is recommended when possible. In cases of ocular cysticercosis, cyst removal rather than enucleation is recommended. Praziquantel and albendazole are effective against the cysticerci. The prognosis for the patient is excellent when the adult worm is present, good when the cysticerci can be surgically removed or medically treated, and poor when the racemose form of the parasite is present, particularly in the brain. It i .s very importa .nt that all patients be i.nstructed to use good personal hygiene if they are found to have a Taenia tapeworm, since there may be a time lag between diagnosis and initiati .on of therapy. There is also a danger of autoinfection with the eggs or possible infection of others. Diagnosis. Identification of adult worms to the species level is not possi ble from the eggs because T. solium and T . saginata eggs look identical. Identification is usually based on the recovery and examination of the gravid proglottids, in which the main uterine lateral branches are counted after India ink injection staining or some other clearing mechanism (7 to 13 for T. solium and 15 to 20 for 7’. saginata). If the scolex is recovered after therapy, then the presence of the four suckers and the armed rostellum with hooks will

CUMITECH

32

differentiate the worm from T. saginata. Since these proglottids contain infective eggs and cannot be identified as to species on first glance, it is very important that personnel use precautions to prevent accidental infection with T. solium eggs, which may lead to cysticercosis. The diagnosis of cysticercosis usually depends on surgical removal of the parasite and microscopic examination for the presence of suckers and hooks on the scolex. Multiple larvae are frequently present, and the presence of cysticerci in the subcutaneous or muscle tissues indicates that the brain is probably also involved. The calcified larvae can be readily seen on X-ray examination. Computerized tomographic scans or magnetic resonance imaging techniques may reveal the presence of lesions in the brain. Ocular cysticercosis can usually be diagnosed by visual identification of the movements and morphology of the larval worm. Although serologic testing can be helpful in some cases, there. may be cross-reactivity between cysticercosis and hydatid infection. Taenia saginata Description, mode of transmission, and prevention. This infection has a worldwide distribution and is generally much more common than T. solium infection, particularly in the United States. The overall impact on human health is much less than that seen with T. solium, since there is no definitive evidence that T. saginata can cause cysticercosis. Infection with the adult worm is initiated by the ingestion of raw or poorly cooked beef containing encysted T. saginata larvae (Fig. 7) (11, 59, 101). As with T. sol&m, the larva is digested out of the meat in the stomach, and the tapeworm evaginates in the upper small intestine and attaches to the intestinal mucosa, where the adult worm matures within 5 to 12 weeks. The adult worm can reach a length of 25 m but often measures only about half this length. Although a single worm is usually found; multiple worms can be present. The scolex has four suckers with no hooks. The proglottids usually number 1,000 to 2,000, with the mature proglottids being more broad than long and the gravid proglottids being narrower and longer. Gravid proglottids often crawl from the anus during the day, when the host is most active. These proglottids may crawl under the stool when a specimen is submitted unpreserved in the stool collection carton. The eggs cannot be distinguished from those of T. solium. They are round to slightly oval, measure 31 to 43 pm, have a thick, striated shell, and contain the six-hooked embryo (oncosphere). The eggs can remain viable in the soil for days to weeks. Upon ingestion by cattle, the oncospheres hatch in the duodenum, penetrate the intestinal wall, and are carried via the lymphatics or bloodstream, where they

Diagnosis

of Zoonotic

Infections

27

are filtered out in the striated muscle. They then develop into the bladder worm or cysticercus within approximately 70 days. The mature cysticercus measures 4 to 6 mm long and contains the immature scolex, which has no hooks (unarmed ). Other animals found to harbor cysticerci include buff alo, giraffe, llama, and possibly reindeer. Since human infection is acquired from the ingestion of raw or poorly cooked beef, all beef prepared for human consumption should be inspected for the presence of cysticerci. Thorough cooking of beef provides complete protection. Human disease and treatment. There are usually few symptoms associated with the presence of the adult worm in the intestine. Although rare symptoms (obstruction, diarrhea, hunger pains, weight loss, appendicitis) have been reported, the most common complaint is the discomfort and embarrassment caused by the proglottids crawling from the anus. This occurrence may be the first clue that the patient has a tapeworm infection. Occasionally, the proglottids may also be seen on the surface of the stool after it is passed. The use of praziquantel or niclosamide has been recommended. The same general approach that is used for T. solium is used to eradicate the adult worm. Therapy is usually very effective. However, if the proglotti .ds begin to reappear in the stool or crawl from the anus, then retreatment will be necessary. Diagnosis. Since the eggs of T. saginata and T. solium look identical, identification to the species level is normally based on the recovery and examination of gravid proglottids. Species identification is usually based on the number of main lateral uterine branches, which are counted on one side of the gravid proglottid. There are between 15 and 20 branches, with an average of 18 for T. saginata, and 7 to 13 for T. solium. Often the gravid proglottids of T. saginata are somewhat larger than those of T. solium; however, this difference may be minimal or impossible to detect. If the scolex is recovered after therapy (which may require purgation), there will be four suckers and no hooks. Spirometra mansonoides and Diphyllobothrium spp. (Sparganosis) Description, mode of transmission, and prevention. In areas where infections are endemic, these organisms can be found in the subcutaneous connective tissue and between the muscles in frogs, lizards, snakes, birds, and certain mammals (11, 22, 59). When these spargana are fed to the definitive hosts (dogs and cats), adult tapeworms develop from several related species of Spirometra. The general name for these spargana is S. mansono tides. Althou & cases have been reported worldwide, sparganosis 1s more common in China, Japan, and Southeast Asia.

28

Evermann

CUMITECH

et al.

Eggs passed from adult tapeworms in the dog or cat intestine hatch in fresh water and are ingested by Cyclops spp., in which they develop into the procercoid larva. When the Cyclops spp. are eaten by a second intermediate host (fish, snakes, amphibians, or mammals), the procercoid larva penetrates the intestinal wall, migrates to the tissues, and develops into the larva (the sparganum). Upon ingestion by a dog or cat, the sparganum develops into the adult tapeworm, thus completing the life cycle. Human infection can occur from (i) ingestion of infected Cyclops spp. (the procercoid sta .ge penetrates the intestinal wall, migrates into tissues, and develops into the sparganum); (ii) ingestion of raw infected flesh of one of the second intermediate hosts (fish, snakes, amphibians, and mammals); and (iii) local application of raw, infected flesh of one of the second intermediate hosts to the skin, conjunctiva, or vagina (the spargana migrate from vertebrate host tissues into human tissue). The spargana are white, ribbonlike worms measuring from a few millimeters to several centimeters long. Considering the possible routes of human infection, all drinking water should be boiled or filtered to prevent accidental ingestion of Cyclops spp. The ingestion of raw tadpole, frog, snake, fowl, or mammalian flesh should be avoided in areas of endemicity. Educational information on the dangers of local application of raw, infected animal flesh (poulticing) to humans, particularly those with ulcerated lesions, should be disseminated. Human disease and treatment. Most patients have slowly growing, tender, subcutaneous nodules that may be migratory. Ocular sparganosis is accompanied by pruritus, pain, lacrimation, and edematous swelling of the eyelid (which may look much like Romana’s sign in Chagas’ disease). There may be elephantiasis (lymph channels), peritonitis (intestinal perforation), and brain abscess. Most patients have leukocytosis and eosinophilia. The sparganum has been reported to live for more than 9 years. Surgical rem0 val is the recommended treatment. Drug therapy is not effective. In the proliferating type of infection, surgical removal is very difficult if not impossible. Diagnosis. Usually diagnosis is not made until drainage of the lesion, surgical removal of the worms, and gross or microscopic examination of the tissue has been performed. The more elongate, wormlike structure of the sparganum can usually be distinguished from the bladder structure of a cysticercus or coenurus, since the latter two have suckers and hooklets, both of which are lacking in a sparganum. Miscellaneous. A variety of tapeworm found in murine hosts (Hymenolepis nana fraterna) is infective for humans (11) and is similar to infections by H. npna.

32

Further information on H. nana infections of humans can be found in reference 59. Trematodes Fasciolopsis buski Description, mode of transmission, and preuention. F. buski is known as the giant intestinal fluke and is one of the largest para sites to infect hu mans (11945, 59) . Adult worms lay unembryonated eggs that are then passed from the intestinal lumen with the feces. The eggs are ellipsoidal, operculate, and yellowbrown. They measure 130 to 140 pm by 80 to 85 pm, with the operculum found at the more pointed end of the transparent egg shell. Depending on the temperature, the eggs embryonate within 3 to 7 weeks. Once in the water, the mature miracidium hatches from the egg and tries to locate the appropriate snail species to infect. After development of sporocysts, rediae, and finally cercariae, the cercariae encyst on water plants such a.s water caltrops, water chestnuts, and water bamboo. Humans become infected by ingesting the raw or undercooked plants containing the metacercariae (Fig. 8). The metacercariae excyst, attach to the duodenal or jejunal mucosa, and develop into adult worms within 3 months. The adult life span seldom exceeds 6 months. F. buski reservoir hosts include dogs, pigs, and rabbits. The infection is commonly found in Bangladesh, Cambodia, the central and southern People’s Republic of China, India, Indonesia, Laos, Malaysia, Pakistan, Taiwan, Thailand, and Vietnam. Drainage of farm waste, use of manure for cultivation, or defecation in or near ponds or lakes that contain the appropriate snails (with water plants acting as vectors) allows the worm’s life cycle to continue. Metacercariae encyst on freshwater vegetation, such as water chestnuts, bamboo shoots, or water caltrops, and the infection is acquired when these infested plants are consumed raw or the outer coat is peeled off the nut with the teeth, resulting in accidental ingestion. To prevent the infection, plants should be cooked or immersed in boiling water for a few seconds before they are eaten or peeled. In areas of endemicity the use of unsterilized night soil for fertilizer should be prohibited. If these safeguards are used, the risk of infection is considerably decreased. Human disease and treatment. The attachment of worms to the mucosal wall prod .uces local inflammation with hypersecretion of mucus, hemorrhage, ulceration, and possible abscess formation. In heavy infections, the worms may cause bowel obstruction, acute ileus, and absorption of toxic or allergic worm metabolites, producing general edema and ascites. A marked eosinophilia and leukocytosis are commonly seen. In heavier infections, the patient may experience

CUMITECH

32

Diagnosis

of Zoonotic

Infections

29

Humans

Metacercariae ingested

T(encysted) by humans

Aduit

f Metacercariae encyst on vegetation or ingested by fish, crabs, or crayfish \

“Orm

Cercariae

Yggs

in feces and/or sputum (must reach wate r

1 Larvae liberated snai I _ . and . penetrate (development of various >r larval forms)

emerge from snail (water) FIGURE

8.

Life cycle

of trematodes

(excluding

schistosomes).

abdominal pain and diarrhea, and the stools are profuse and yellow-green, containing increased amounts of undigested food, suggesting a malabsorption process.Depending on the worm burden, the diseasecan be fatal. Praziquantel is recommended as the drug of choice. Diagnosis. The diagnosis is suggestedby the clinical features in areas where infections are endemic and is confirmed by detecting the eggsin the stool. The eggs of E. ilocanum, F. hepatica, and F. buski are similar in size and shape; therefore, an exact identification cannot be made from examining the eggs. It is possible to detect adult worms in the stool in heavy infections when they lose their ability to remain attached to the intestinal mucosa. Echinostoma ilocanum Description, mode of transmission, and prevention. A number of speciesof echinostomeshave been reported to infect humans. Most of the speciesare found in oriental countries; E. ilocanum is the most important species(l&22,45,59). Adult worms are attached to the mucosal wall of the small intestine and lay eggs, which are passed from the intestinal lumen in the feces. Eggs are immature, ellipsoidal, yellow-brown, and operculated. Egg size is 86 to 116 km by 58 to 69 pm. The miracidia take 1 to 2 weeks to mature in the environment before they hatch from the eggs and infect the snail intermediate host. Two or more generations of rediae are produced before cercariae develop. These cercariae encyst in freshwater mollusks, and humans are infected by eating these raw mollusks. The metacercariae hatch in the intestine, attach to the mucosal wall, and develop into mature adult worms. The adults are
Reprinted

from

reference

59 with

permission.

found to be infected in areas where infections are endemic. The infection has been reported in China, Indonesia, Thailand, the Philippines, and the Celebes. The cercariae can encyst in a number of freshwater mollu .sks, particularly snails. If infected mollusks are eaten raw, the metacercariae will excyst in the intestinal tract and develop into adult worms. The infection can be prevented in areas of endemicity by restricting the use of night soil for fertilizer and eating cooked rather than raw mollusks. Human diseaseand treatment. With light infections, the patient may be asymptomatic, and the adult worms cause only minor pathology other than localized inflammation. In heavy infections, the worms can produce catarrhal inflammation and mild ulceration, and the patient may experience diarrhea and abdominal pain. Diagnosis. Eggs of E. ilocanum can be detected in the stool. They are the samesize (some strains) and shape as the eggsof F. hepatica and F. buski. Becauseof the size range overlap, exact identification cannot be made from the eggs,and the diagnosis may have to be made on the basis of patient history or clinical find mgs. Clonorchis sinensis Description, mode of transmission, and prevention C. sinensis is also known as the Chinese or oriental liver fluke (11,59,101). Adult worms deposit eggsin the bile ducts, and the eggs are discharged with the bile fluid into the feces and passedout into the environment. The eggs are fully embryonated when laid and measure 28 to 35 pm by 12 to 19 pm. The eggs are ovoid, with a thick, light brownish yellow shell and an operculum. There are distinct opercular shoulders surrounding the operculum. Frequently, the eggs contain a comma-shaped appendage at the abopercular end. Eggs are ingested by the snail host, at which time the miracidium hatches to infect the snail. Sporocyst and rediae generations are produced before

30

Evermann

CUMITECH

et al.

cercariae are released to encyst in the skin or flesh of freshwater fish. Humans become infected by ingesting the metacercariae in uncooked fish (Fig. 8). Metacercariae excyst in the duodenum, enter the common bile duct, and travel to the distal bile capillaries, where the worms mature. The life cycle takes approximately 3 months to complete in humans. Humans, dogs, cats, and other fish-eating mammals are reservoir hosts and, in some areas, the sole cause for continual transmission. The infection is found in China, Japan, Korea, Malaysia, Singapore, Taiwan, and Vietnam. Natives of Hawaii have also been found to harbor the infection, which was contracted through the ingestion of frozen, pickled, or dried fish imported from areas of endemicity. Human infections result from the widely prevalent practice of consumption of metacercaria-infested freshwater fish eaten uncooked, pickled, smoked, salted, or dried. The life cycle is perpetuated by humans or reservoir hosts defecating in or near freshwater sources containing suitable species of snails. In areas where fish cultivation is of economic importance, toilets have been built over ponds to provide a source of fish food. Operculate snails noted to be infected are Parafossarulus, Bulinus, Semisulcospira, Alocinma, and Melanoides spp. Metacercariae will encyst in numerous species of freshwater fish. The life cycle can be broken and infection can be prevented in humans by thorough cooking of all freshwater fish. Although cultural habits are difficult to change, public health education can be used to modify them. Night soil used for fertilizer without disinfection should not be used in lakes or ponds containing susceptible snails. Human disease and treatment. In light infections, the patient generally experiences no symptoms. In heavier infections acquired over time, the patient may experience dull pain and abdominal discomfort that may last 1 to 2 h, often in the afternoon. As the disease progresses, the duration of pain lengthens and may become so severe that the patient is unable to work. Patients who have had the disease for a prolonged period will have liver enlargement with some degree of functional impairment that is secondary to biliary obstruction. Acute infections caused by ingestion of large numbers of metacercariae will, within a month, cause fever, chills, diarrhea, epigastric pain, enlarged tender liver, and possibly jaundice. The acute symptoms last for about 1 month and subside at about the time eggs are detected in the stool. Praziquantel or albendazole is recommended for therapy. Diagnosis. Eggs of C. sinensis can be detected in the stool. They are the same size (some strains) and shape as the eggs of several other small trematodes. Because of the size range overlap, exact identification may be difficult from the eggs, and the diagnosis may have to

32

be made on the basis of patient history or clinical findings. Opisthorchis Description, 0. viverrini

viverrini mode of transmission,

and prevention.

has been reported to infect a significant portion of the population in northern Thailand and Laos (22, 59, 101). Infection with 0. viverrini has been associated with carcinoma of the bile duct epithelium (cholangiocarcinoma). Adult worms in distal bile ducts produce eggs that are carried by the bile to the intestinal lumen, and then to the outside environment in the feces. The eggs are brownish yellow, oval, and operculated, have opercular shoulders, and may have a comma-shaped appendage at the abopercular end. Egg size averages 27 by 15 pm. The life cycle is similar to that of C. sinensis, requiring developmental periods in the susceptible snail and finally freshwater fish, in which the metacercariae encyst. Metacercariae excyst in the duodenum of the mammalian host and migrate to the intrahepatic bile ducts, where they develop into mature adults. Dogs, cats, and other fish-eating mammals including humans are reservoir hosts. The infection has been reported to occur in Cambodia, Laos, and Thailand. Human infections result from consumption of metacercariae-infested freshwater fish eaten uncooked, pickled, smoked, salted, or dried. Bithynia snails are the first intermediate hosts, and freshwater fish are the second intermediate hosts. Public health education should be employed to advise the population at risk in areas where infections are endemic of the hazards of eating uncooked fish. This approach has not met with much success because of the difficulty in disrupting established cultural and dietary traditions. Also, defecation in or near ponds or lakes should be prevented, as should the application of night soil where the intermediate hosts are abundant. Human disease and treatment. As with C. sinensis, the pathology is mainly confined to the biliary tract system, and morbidity is associated with the worm burden of the host. Clinical signs of abdominal pain, flatulence, weakness, hepatomegaly, cholangitis, chronic cholecystitis, cholelithiasis, and obstructive jaundice become more common as the number of infecting worms increases. A large number of individuals with 0. viverrini infection have cholangiocarcinomas, which were also seen at autopsy. Praziquantel is the drug of choice. Diagnosis. The eggs of C. sinensis and 0. viverrini are similar in size and shape. Differentiation is difficult without a patient history and is based on measurements of a large number of eggs. Multiple stool examinations may be required to detect light infections because of lack of sensitivity of concentration techniques used for stool examination. Although serologic

CUMITECH

32

diagnostic tests to detect specific antibodies have been developed, the tests are not widely available, are not standardized, and give false-positive results due to cross-reactivity with other parasitic agents. Fasciola hepatica Description, mode of transmission, and prevention. Fascioliasis is primarily a zoonotic disease that results in liver infections by adult flukes (11,22,45,59,101). Although the disease has a cosmopolitan distribution, only a single case of autochthonous infection in a human has been reported in the United States. Adult worms, which may live for 9 years in the bile ducts, produce eggs that are carried by the bile fluid into the intestinal lumen and passed into the environment with the feces. The eggs are unembryonated, operculated, large, ovoid, and brownish yellow and measure 130 to 150 pm by 63 to 90 pm. The miracidium develops within 1 to 2 weeks and escapes from the egg to infect the snail intermediate host, Lymnaea sp. Cercariae are liberated from the snail after the production of a sporocyst generation and two or three rediae generations. Cercariae encyst on water vegetation, such as watercress. Humans are in .fected by ingestion of uncooked aquatic vegetation on which metacercariae excyst in the are encysted (Fig. 8). Metacercariae duodenum and migrate through the intestinal wall into the peritoneal cavity. The larvae enter the liver by penetrating the capsule (Glisson’s capsule) and wander through the liver parenchyma for up to 9 weeks. The larvae finally enter the bile ducts, where they mature and produce eggs, which are passed out in feces. The largest numbers of infections have been reported from Bolivia, Ecuador, Egypt, France, Iran, Peru, and Portugal. Although animal fascioliasis is endemic throughout the Americas, human infections are rare in most countries. Reservoir hosts include herbivores such as cattle, goats, and sheep. The reservoir hosts, primarily sheep, play an important role in the propagation of this infection in nature. Animal fascioliasis is a major veterinary problem in Europe. The infection is contracted by the ingestion of metacercariae encysted on uncooked water plants, such as watercress. Watercress is the main source of infection, and in many countries, wild watercress is touted as a healthy natural food. In many areas of the world, animal manure is used as the primary fertilizer for cultivation of watercress. Prevention may be accomplished by public health education, stressing the dangers of eating watercress grown in the wild where animals and snails are abundant. Other measures have included eliminating mollusks, treating infected animals, and draining pasture lands. Human disease and treatment. The amount of tissue damage depends on the worm burden of the host.

Diagnosis

of Zoonotic

Infections

31

Symptoms associated with the migratory phase have included fever, epigastric and right upper quadrant pain, and urticaria. However, some patients may experience no symptoms. Leukocytosis, eosinophilia, and mild to moderate anemia may be found in many patients. Levels of IgG, IgM, and IgE in serum are usually elevated. In sheep, the migratory phase produces such extensive liver parenchyma damage that the disease is known as liver rot. Symptoms and signs of infection during the late stages, after egg production has begun, are those associated with biliary obstruction and cholangitis. Acute epigastric pain, fever, pruritus, jaundice, hepatomegaly, and eosinophilia are common. Bithional or triclabendazole is recommended for therapy. In areas of endemicity, such as Lebanon, where uncooked liver may be eaten, adult worms may attach to the pharyngeal mucosa, producing suffocation (halzoun syndrome). This condition is temporary, although it may produce considerable discomfort. Diagnosis. The eggs of F. hepatica, Fasciolopsis buski, and E. ilocanum are similar in size and shape. Differentiation may be difficult without a patient history. Multiple stool examinations may be needed to detect light infections. Eggs may be detected in the stool of individuals who have eaten F. hepatica-infected liver, thereby yielding an erroneous laboratory result. Serologic tests are preferred for diagnosis of acute and chronic fascioliasis when few eggs can be found in the stool or when large populations are screened. Paragonimus spp. Description, mode of transmission, and prevention. Paragonimiasis is a disease of humans and carnivores in which adult flukes of the genus Paragonimus are found in the lungs (8,11,22,45,59,97). Since 1899, the name Paragonimus westermani has been used. P. mexicanus is an important human pathogen in Central and South America. The majority of the infections of paragonimiasis are caused by P. westermani. The adult worm is a plump, ovoid, reddish brown fluke found encapsulated in the lung. Eggs deposited by the worms are ovoid, brownish yellow, unembryonated, and thick shelled, with an operculum at one end and opercular shoulders. Eggs measure 80 to 120 pm by 45 to 65 Frn. P. westermani eggs are often confused with Diphyllobothrium eggs because both are operculated, unembryonated, and somewhat similar in size. P. westermani eggs have opercular shoulders and a thickened shell at the abopercular end. Eggs escape from the encapsulated tissue through the bronchioles, are coughed up and voided in the sputum, or are swallowed and passed out in the feces. The eggs hatch in the water in 2 to 3 weeks, releasing a miracidium to infect a susceptible snail host. Cercariae are released after sporocyst and rediae develop from the miracidium. Crabs and crayfish are infected

32

Evermann

et al.

by cercariae via the gill chamber or upon ingestion of an infected snail. Cercariae encyst in the gill vessels and muscles. Humans are infected by ingesting uncooked crabs or crayfish containing metacercariae (Fig. 8). The metacercariae excyst in the duodenum and migrate through the intestinal wall into the abdominal cavity. The larvae migrate around or through the diaphragm into the pleural cavity and the lungs. The larvae mature to adults in the vicinity of the bronchioles, where they discharge their eggs into the bronchial secretions. Reservoir hosts include dogs and cats in areas of endemic infection (Far East and Africa). Eggs expectorated or passed in the feces in the vicinity of lakes or streams where the intermediate hosts live serve as the source of infection. In most areas, the disease is primarily one of crab- or crayfish-eating mammals, with humans being incidental hosts. Measures devoted to public health education, warning people of the dangers of eating uncooked crabs or crayfish from areas of endemic infection, and sanitary care of utensils and fingers used to prepare food would reduce the risk of infection. Because the cycle depends on animals, the elimination of human paragonimiasis would have little effect on the overall prevalence of the disease. Human disease and treatment. Symptoms of paragonimiasis depend largely on the worm burden of the host and are usually insidious in onset and mild in chronic cases. Light infections may be asymptomatic, although peripheral blood eosinophilia and lung lesions may be noted on X rays. As the cysts rupture, a cough develops with increased production of viscous bloodtinged sputum and increased chest pain. The patient may experience increasing dyspnea with chronic bronchitis and be misdiagnosed as having tuberculosis. There will be a moderately high peripheral blood eosinophilia and leukocytosis with elevated serum IgG and IgE. The most serious consequence of paragonimiasis is cerebral complications, which are commonly found in younger age groups. Most patients with extrapulmonary lesions have an associated lung lesion or a history of lung disease. Symptoms include fever, headache, nausea, vomiting, visual disturbances, motor weakness, localized or generalized paralysis, and possibly death. Abdominal or subcutaneous masses are frequently seen in infections caused by P. skrjabini, P. heterotremus, and P. mexicanus. Praziquantel or bithional is recommended for therapy. Diagnosis. Individuals with symptoms of chronic cough, vague chest pains, and hemoptysis from an area of endemicity and a history of eating raw crayfish or crabs should be suspected of having paragonimiasis. Paragonimus eggs can be detected in sputum and in the stool. Therefore, both specimens should be examined. In many individuals in whom the infection

CUMITECH

32

is eventually confirmed, small numbers of eggs are present intermittently in the sputum and feces. Frequently, pulmonary paragonimiasis is misdiagnosed as pulmonary tuberculosis. The Ziehl-Neelsen method for detecting mycobacteria destroys the eggs of Paragonimus. Serology-based assays are available in areas of endemicity or in specialized diagnostic centers. Most of these assays used nonstandardized reagents and have not been used in clinical trials. ACKNOWLEDGMENTS We thank our technical staff, in particular Alison J. McKeirnan, for laboratory assistance. We also thank Ronald F. DiGiacomo, who provided insights into epidemiological problems. Thanks are extended to Danielle Bishop for editorial and word processing assistance.

1. Acha, P. N., and B. Szyfres. 1987. Bovine papular stomatitis, p. 302-303. In Zoonoses and Communicable Diseases Common to Man and Animals, 2nd ed. Pan American Health Organization, Washington, D.C. 2, Acha, I?. N., and B. Szyfres. 1987. Contagious ecthyma, p. 315-317. In Zoonoses and Communicable Diseases Common to Man and Animals, 2nd ed. Pan American Health Organization, Washington, D.C. 3. Acha, P. N., and B. Szyfres. 1987. Pseudocowpox, p. 422-425. In Zoonoses and Communicable Diseases Common to Man and Animals, 2nd ed. Pan American Health Organization, Washington, D.C. 4. Acha, I?. 425-449. Common can Health

N., and B. Szyfres. 1987. Rabies, p. In Zoonoses and Communicable Diseases to Man and Animals, 2nd ed. Pan AmeriOrganization, Washington, D.C.

5. Acha, I?. N., and B. Szyfres. 1987. Vesicular stomatitis, p. 506-512. In Zoonoses and Communicable Diseases Common to Man and Animals, 2nd ed. Pan American Health Organization, Washington, D.C. I Ja.Acha, I?. N., and B. Szyfres. 1987. Q fever, p. 261-267. In Zoonoses and Communicable Diseases Common to Man and Animals, 2nd ed. Pan American Health Organization, Washington, D.C. 6. Allan, J. S. 1995. Xenograft transplantation and the infectious disease conundrum. Inst. Lab. Anim. Res. J. 37:37-48. 7. Anderson, L. J., W. G. Winkler. States, 1960 to prevention. Ann.

K. G. 1985. 1979: Intern.

Nicholson, R. Human rabies epidemiology, Med. 100:728

V. Tauxe, and in the United diagnosis, and -735.

8. Ash, L. R., and T. C. Orihel. 1997. Atlas of Human Parasitology, 4th ed. ASCP Press, Chicago, Ill. 9. Beard, C. W. 1992. Avian influenza, p. 37-40. In A. E. Castro and W. P. Heuschele (ed.), Veterinary Diagnostic Virology. A Practitioner’s Guide. Mosby Yearbook, St. Louis, MO. 10. Beard, C. W. 1992. Newcastle

disease, p. 54-56.

In

CUMITECH

32

Diagnosis

A. E. Castro and W. I?. Heuschele (ed.), Veterinary Diagnostic Virology. A Practitioner’s Guide. Mosby Yearbook, St. Louis, MO.

26. Buhariwalla, dog-related 23:753-75.5.

of Zoonotic

Infections

33

F., B. Cann, and T. J. Marrie. 1996. A outbreak of Q fever. Clin. Infect. Dis.

11. Beaver, I? C., R. C. Jung, and E. W. Cupp. 1984. Clinical Parasitology, 9th ed. Lea & Febiger, Philadelphia, Pa.

27. Butler, J. C., and C. J. Peters. 1994. Hantaviruses and hantavirus pulmonary syndrome. Clin. Infect. Dis. 19:387-39.5.

12. Behymer, D. E., C. E. Franti, M. Crenshaw. 1976. gations in dairy vaccination. Am.

28

Calisher, C. H., N. Karabatsos, H. Zeller, J. I?. Digoutte, R. B. Tesh, R. E. Shope, A. P. A. \TravasSOS da Rosa, and T. D. St. George. 1989. Antigenic relationships among rhabdoviruses from vertebrates and hematophagous arthropods. Intervirology 30: 241-257.

29

Center for Disease Control. 1977. Rabies in a laboratory worker - New York. Morbid. Mortal. Weekly Rep. 26:183-186.

E. L. Biberstein, H. I?. Riemann, Sawyer, R. Ruppanner, and G. L. Q fever (Coxiella burnetii) investicattle: challenge of immunity after J. Vet. Res. 37:631-634.

13. Benenson, A. S. 1995. Arenaviral hemorrhagic fevers in South America, p. 22-25. In Control of Communicable Diseases Manual, 16th ed. American Public Health Association, Washington, D.C. 14. Benenson, A. S. 1995. Lassa fever, p. 2.53-256. In Control of Communicable Diseases Manual, 16th ed. American Public Health Association, Washington, D.C.

30. Centers for Disease Control. 1991. Rabies prevention -United States, 199 1. Recommendations of the Immunization Practices Advisory Committee (ACIP). Morbid. Mortal. Weekly Rep. 40(RR-03):1-19.

15. Benenson, A. S. 1995. Q fever, p. 379-382. In Control of Communicable Diseases Manual, 16th ed. American Public Health Association, Washington, D.C.

31. Centers for Disease Control and Prevention. 1992. Extension of the raccoon rabies epizootic-United States, 1992. Morbid. Mortal. Weekly Rep. 41: 661-664. .

16. Bennett, M., and M. E. Begon. 1997. Virus zoonoses: a long-term overview. Comp. Immunol. Microbiol. Infect. Dis. 20:101-109.

32 Centers for Disease Control and Prevention. 1993. Rickettsial agents, p. 102-103. In J. Y. Richmond and R. W. McKinney (ed.), Biosafety in Microbiological and Biomedical Laboratories, 3rd ed. U.S. Department of Health and Human Services, Washington, D.C.

17. Beran, G. W. 1991. Urban rabies, p. 427-443. In G. M. Baer (ed.), The Natural History of Rabies, 2nd ed. CRC Press, Boca Raton, Fla. 18. Beran, G. W. 1994. Rabies and infections by rabiesrelated viruses, p. 307-357. ln G. W. Beran and J. H. Steele (ed.), Handbook of Zoonoses, Section B: Viral, 2nd ed. CRC Press, Boca Raton, Fla. 19. Berge, T. O., and E. H. Lennette. 1953. World distribution of Q fever: human, animal and arthropod infection. Am. J. Hyg. 57:125-127. 20. Bernard, K. W., G. L. Parham, W. G. Winkler, and C. G. Helmick. 1982. Q fever control measures: recommendations for research facilities using sheep. Infect. Control 3:461-46X 21. Biberstein, E. L., H. P. Riemann, C. E. Franti, D. E. Behymer, R. Ruppanner, R. Bushnell, and G. Crenshaw. 1977. Vaccination of dairy cattle against Q fever (Coxiella burnetii): results of field trials. Am. J. Vet. Res. 38:189-193. 22. Binford, C. H., and D. H. Connor. 1976. Pathology of Tropical and Extraordinary Diseases. Armed Forces Institute of Pathology, Washington, D.C. 23. Bingham, J., F. W. G. Hill, and R. Matema. 1994. Rabies incubation in an African civet (Civettictis civetta). Vet. Rec. 134528 -532. 24 . Bourhy, H., B. Kissi, and N. Tordo. 1993. Molecular diversity of the lyssavirus genus. Virology 194:70-81. 25 . aBrown, C. 1997. Emerging diseases: what veterinari;ans need to know. J. Vet. Diag. Invest. 9:113-l 17.

33. Centers for Disease Control and Prevention. 1993. Agent summary statements-viral agents, rabies, p. 115-l 16. In J. Y. Richmond and R. W. McKinney (ed.), Biosafety in Microbiological and Biomedical Laboratories, 3rd ed. U.S. Department of Health and Human Services, Washington, D.C. 34. Centers for Disease Control and Prevention. 1993. Agent summary statements -viral agents, vesicular stomatitis, p. 122-123.1n J. Y. Richmond and R. W. McKinney (ed.), Biosafety in Microbiological and Biomedical Laboratories, 3rd ed. U.S. Department of Health and Human Services, Washington, D.C. 35. Centers for Disease Control and Prevention. 1994. Progress in the development of hantavirus diagnostic assays -United States. Morbid. Mortal. Weekly Rep. 42:770-771. 36. Centers for Disease Control and Prevention. 1994. Recommendations and Reports: Laboratory management of agents associated with hantavirus pulmonary syndrome: interim biosafety guidelines. Morbid. Mortal. Weekly Rep. 43:1-7. 37. Centers for Disease Control and Prevention. Newly identified hantavirus - Florida. Morbid. tal. Weekly Rep. 43:99-105.

1994. Mor-

38

1994. 1993.

Centers for Disease Control and Prevention. Raccoon rabies epizootic-United States, Morbid. Mortal. Weekly Rep. 43:269 -273.

39< Centers for Disease Control

and Prevention.

1994.

34

Evermann

et al.

CUMITECH

Hantavirus pulmonary United States. Morbid. 548 -.549,SSS-556.

syndrome -northeastern Mortal. Weekly Rep. 43:

40

Centers for Disease Control Human rabies-Washington, Weekly Rep. 44:62S- 627.

41

Centers for Disease Control and Prevention. 1997. Compendium of animal rabies control, 1997. National Association of State Public Health Veterinarians, Inc. Morbid. Mortal. Weekly Rep. 46:1-9.

42

43

and Prevention. 1995. 1995. Morbid. Mortal.

Childs, J. E., T. G. Ksiazek, C. F. Spiropoulou, J. W. Krebs, S. Morzunov, G. 0. Maupin, K. L. Gage, P. E. Rollin, J. Sarisky, and R. E. Enscore. 1994. Serologic and genetic identification of Peromyscus maniculatus as the primary rodent reservoir for a new hantavirus in the southwestern United States. J. Infect. Dis. 169:1271-1280. Clark, K. A., S. U. Neil, J. S. Smith, P. J. Wilson, V. W. Whadford, and G. W. McKirahan. 1994. Epizootic canine rabies transmitted by coyotes in south Texas. J. Am. Vet. Med. Assoc. 204:536-540.

44. Constantine, D. G. 1971. Bat rabies: current knowledge and future research, p. 253-265. In Y. Nagano and F. M. Davenport (ed.), Rabies. University Park Press, Baltimore, Md. 4s. Cook, G. C. 1996. Manson’s Tropical Diseases, 20th ed. The W. B. Saunders Co., Philadelphia, Pa. 46. Couch, R. B., and J. A. Kasel. 1995. Influenza, p. 431-446. In E. H. Lennette, D. A. Lennette, and E. T. Lennette (ed.), Diagnostic Procedures for Viral, Rickettsial, and Chlamydial Infections, 7th ed. American Public Health Association, Washington, D.C. 47. De Jong, J. C., E. C. J. Claas, A. D. M. E. Osterhaus, R. G. Webster, and W. L. Lim. 1997. A pandemic warning? Nature 389:SS4. 48. Deutch, E. L., and E. T. Peterson. 1950. Q fever: transmission from one human being to others. JAMA 143:348-351. 49. Douron, E., B. Moriniere, S. Matheron, P. M. Girard, J. P. Gonzalex, F. Hirsch, and J. B. McCormick. 1984. HFRS after a wild rodent bite in the Haute-Savoie-and risk of exposure to hantaan-like virus in a Paris laboratory. Lancet i:676-677. 50. Duchin, J. S., F. T. Koster, D. J. Peters, G. L. Simpson, B. Tempest, S. R. Zaki, T. G. Ksiazek, P. E. Rollin, S. Nichol, E. T. Umland, R. L. Moolenaar, S. E. Reef, K. B. Nolte, M. M. Gallaher, J. C. Butler, R. F. Breiman, and the Hantavirus Study Group. 1994. Hantavirus pulmonary syndrome: a clinical description of 17 patients with a newly recognized disease. N. Engl. J. Med. 330:949-955. Sl. Easterday, B. C. 1992. Equine influenza, p. 169-171. In A. E. Castro and W. I?. Heuschele (ed.), Veterinary Diagnostic Virology. A Practitioner’s Guide. Mosby Yearbook, St. Louis, MO. 52. Easterday,

B.

C.

1992.

Porcine

influenza,

p.

32

230-232. In A. E. Castro and W. P. Heuschele (ed.), Veterinary Diagnostic Virology. A Practitioner’s Guide. Mosby Yearbook, St. Louis, MO. 53. Feldmann, H., W. Slenczka, and H. D. Klenk. 1996. Emerging and reemerging of filoviruses, p. 77-100. In T. F. Schwarz and G. Siegl (ed.), Imported Virus Infections. Springer-Verlag, Vienna, Austria. 54. Fenner, F. 1994. Poxviral zoonoses, p. 485-503. 1n G. W. Beran and J. H. Steele (ed.), Handbook of Zoonoses, Section B: Viral, 2nd ed. CRC Press, Boca Raton, Fla. 5s. Fields, B. N., and K. Hawkins. 1967. Human infection with the virus of vesicular stomatitis during an epizootic. N. Engl. J. Med. 277:989-994. 56. Francy, D. B., C. G. Moore, G. C. Smith, W. L. Jakob, S. A. Taylor, and C. H. Calisher. 1988. Epizootic vesicular stomatitis in Colorado, 1982: isolation of virus from insects collected along the northern Colorado Rocky Mountain front range. J. Med. Entomol. 25343-346. 57. Friedland, J. S., I. Jeffrey, G. E. Griffin, M. Booker, and R. Courtenay-Evans. 1994. Q fever and intrauterine death. Lancet 343:288. (Letter.) 58. Fries, L. R., D. M. Waag, and J. C. Williams. 1993. Safety and immunogenicity in human volunteers of a chloroform: methanol residue vaccine for Q fever. Infect. Immun. 61:12Sl-1256. 58a.Garcia, L. S. 1998. Laboratory methods for diagnosis of parasitic infections, p. 783-869. In B. A. Forbes, D. F. Sahm, and A. S. Weissfeld (ed.), Bailey and Scott’s Diagnostic Microbiology, 10th ed. The C. V. Mosby Co., St. Louis, MO. 59. Garcia, L. S., and D. A. Bruckner. 1997. Diagnostic Medical Parasitology, 3rd ed. ASM Press, Washington, D.C. 60. Gearhart, M. A., P. A. Webb, A. P. Knight, M. D. Salman, J. A. Smith, and G. A. Erickson. 1987. Serum neutralizing antibody titers in dairy cattle administered in inactivated vesicular stomatitis virus vaccine. J. Am. Vet. Med. Assoc. 191:819-822. 61

Georges-Courbot, M.-C., A. Sanchez, C.-Y. Lu, S. Baize, E. Leroy, J. Lansout-Sourkate, C. Tevi-Benissan, A. J. Georges, S. G. Trappier, S. R. Zaki, R. Swanepoel, P. A. Leman, P. E. Rollin, C. J. Peters, S. T. Nichol, and T. G. Ksiazek. 1997. Isolation and phylogenetic characterization of Ebola viruses causing different outbreaks in Gabon. Emerg. Infect. Dis. 3:11-14.

62 Gill, D. M., and D. M. Stone. 1992. The veterinarian’s role in the AIDS crisis. J. Am. Vet. Med. Assoc. 201:1683-1684. 63. Gould, A. R. 1996. Comparison of the deduced matrix and fusion protein sequences of equine morbillivirus with cognate genes of the Paramyxoviridae. Virus Res. 43:17-31. 64. Guichon, A., T. J. Inzana, J. M. Scimeca, and A. Zajac. 1996. Cumitech 28, Laboratory Diagnosis of

CUMITECH

32

Diagnosis

Zoonotic Infections: Chlamydial, Fungal, Viral, and Parasitic Infections 0 btained from Companion and Laboratory Animals. Coordinating ed., T. J. Inzana. American Society for Microbiology, Washington, D.C. 65. Hanson, R. I? 1952. The natural history of vesicular stomatitis virus. Bacterial. Rev. 16: 179 -204. 66. Hanson, R. P., A. F. Rasmussen, C. A. Brandly, and J. W. Brown. 1950. Human infection with the virus of vesicular stomatitis. J. Lab. Clin. Med. 36:754758. 67. Harman, J. B. 1949. Q fever in Great Britain; cal account of eight cases. Lancet 2:1028-1031.

clini-

68. Hicks, B. D., and G. A. J. Worthy. 1987. Sealpox in captive grey seals (Halichoerus grypus) and their handlers. J. Wildl. Dis. 23:1- 6. N. Torrez-Martinez, S. 69 . Hjelle, B., C. F. Spiropoulou, Morzunov, C. J. Peters, and S. T. Nichol. 1994. Detection of Muerto Canyon virus in peripheral blood mononuclear cells from patients with hantavirus pulmonary syndrome. J. Infect. Dis. 170:1013-1017. 70. Hopper, P. T., A. R. Gould, G. M. Russell, J. A. Kattenbelt, and G. Mitchell. 1996. The retrospective diagnosis of a second outbreak of equine morbillivirus infection. Aust. Vet. J. 74:244-245. 71. Hugh-Jones, M. E., W. T. Hubbert, and H. V. Hagstad. 1995. Principles of zoonoses control and prevention: prevention, control, and eradication, p. 79 -120. In Zoonoses: Recognition, Control, and Prevention. Iowa State University Press, Ames. 72. Hugh-Jones, M. E., W. T. Hubbert, and H. V. Hagstad. 1995. Role of the laboratory in zoonoses recognition, p. 49 -78. In Zoonoses: Recognition, Control, and Prevention. Iowa State University Press, Ames. and H. V. 73. Hugh-Jones, M. E., W. T. Hubbert, Hagstad. 1995. Q fever, p. 296-297. In Zoonoses, Recognition, Control, and Prevention. Iowa State University Press, Ames. 74. Hugh-Jones, M. E., W. T. Hubbert, and H. V. Hagstad. 1995. Viral zoonoses, p. 301-353. In Zoonoses: Recognition, Control, and Prevention. Iowa State University Press, Ames. 75. Hyatt, A. D., and P. W. Selleck. 1996. Ultrastructure of equine morbillivirus. Virus Res. 43:1-15. 76. Isenberg, H. D. 1992. Clinical Microbiology Procedures Handbook. American Society for Microbiology, Washington, D.C. 77. Jahrling, P. B. 1995. Arenaviruses and filoviruses, p. 213-229. In E. H. Lennette, D. A. Lennette, and E. T. Lennette (ed.), Diagnostic Procedures for Viral, Rickettsial, and Cblamydial Infections, 7th ed. American Public Health Association, Washington, D.C. 78. Jenison, S., T. Yamada, C. Morris, B. Anderson, N. Torrez-Martinez. N. Keller. and B. Hielle. 1994.

of Zoonotic

Infections

35

Characterization of human antibody responses to Four Corners hantavirus infections among patients with hantavirus pulmonary syndrome. J. Virol. 68:467-472. 79. Jenkins, S. R., B. D. Perry, and W. G. Winkler. 1988. Ecology and epidemiology of raccoon rabies. Rev. Infect. Dis. 10:620-625. 80. Kamolvarin, N., T. Tirawatnpong, R. Rattanasiwamoke, S. Tirawatnpong, T. Panpanich, and T. Hemachudha. 1993. Diagnosis of rabies by polymerase chain reaction using nested primers. J. Infect. Dis. 167:207-210. 81. Khan, M. I. 1994. Newcastle disease, p. 473-481. In G. W. Beran and J. H. Steele (ed.), Handbook of Zoonoses, Section B: Viral, 2nd ed. CRC Press, Boca Raton, Fla. 82. Khan, A. S., M. Gaviria, P. E. Rollin, W. G. Hlady, T. G. Ksiazek, L. R. Armstrong, R. Greenman, E. Ravkow, M. Kolber, H. Anapol, E. D. Sfakianaki, S. T. Nichol, C. J. Peters, and R. F. Khabbaz. 1996. Hantavirus pulmonary syndrome in Florida: association with a newly identified Black Creek Canal hantavirus. Am. J. Med. 100:46-48. 83. Khan, A. S., R. F. Khabbaz, L. R. Armstrong, R. C. Holman, S. P. Bauer, J. Graber, T. Strine, G. Miller, S. Reef, J. Tappero, P. E. Rollin, S. T. Nichol, S. R. Zaki, R. T. Bryan, L. E. Chapman, C. J. Peters, and T. B. Ksiazek. 1996. Hantavirus pulmonary syndrome: the first 100 cases. J. Infect. Dis. 173:12971303. 84 Khan, A. S., C. F. Spiropoulou, S. Morzunov, S. R. Zaki, M. A. Kohn, S. R. Nawas, L. McFarland, and S. T. Nichol. 1995. A fatal illness associated with a new hantavirus in Louisiana. J. Med. Virol. 46:281286. 85. Kida, H., T. Ito, K. Okazaki, Y. Kawaoka, and R. G. Webster. 1996. Avian influenza viruses as the origin of pandemic strains: perpetuation in nature and potential for transmission to pigs, p. 529-536. In L. E. Brown, A. W. Hampson, and R. G. Webster (ed.), Options for the Control of Influenza III. Elsevier Science Publishers, Amsterdam, The Netherlands. 86, Kimwa, H., C. Aliko, G. Peng, Y. Muraki, K. Sugawara, S. Hengo, F. Kitame, K. Mizata, Y. Namaki, H. Suzuki, and K. Nakamura. 1997. Interspecies transmission of influenza C virus between humans and pigs. Virus Res. 48:71-79. 87. Kissi, B., N. Tordo, and H. Bourhy. 1995. Genetic polymorphism in the rabies virus nucleoprotein gene. Virology 209:526-537. 88. Kleiman, M. B., and D. S. Leland. 1995. Mumps virus and Newcastle disease virus, p. 460-463. In E. H. Lennette, D. A. Lennette, and E. T. Lennette (ed.), Diagnostic Procedures for Viral, Rickettsial, and Chlamydial Infections, 7th ed. American Public Health Association. Washington, D.C.

36

Evermann

et al.

CUMITECH

89. Kosatsky, T. 1984. Household outbreak of Q fever pneumonia related to a parturient cat. Lancet 2:1447-1449. 90. Krebs, J. W., T. C. E. Rupprecht, veillance in the Vet. Med. Assoc.

W. Strine, J. S. Smith, D. L. Noah, and J. E. Childs. 1996. Rabies surUnited States during 1995. J. Am. 209:2031-2044.

91. Langley, J. M., T. J. Marrie, A. Covert, D. M. Waag, and J. C. Williams. 1988. Poker players’ pneumonia: an urban outbreak of Q fever following exposure to a parturient cat. N. Engl. J. Med. 319:354-356. 92. Lauerman, L. H., and R. P. Hanson. 1964. Field trial of live virus vaccination procedure for prevention of vesicular stomatitis in dairy cattle. III. Evaluation of emergency vaccination in Georgia. Proc. 67th Annual Meeting, U.S. Livestock Sanit. Assoc. 67:473-482. 93. LeDuc, J. W. 1987. Epidemiology of hantaan and related viruses. La6 Anim. Sci. 37:413-418. 94. Lee, H. W., L. J. Baek, and K. M. Johnson. 1982. Isolation of hantaan virus, the etiologic agent of Korean hemorrhagic fever, from wild urban rats. J. Infect. Dis. 146:638 -644. 95. Lee, H. W., and K. M. Johnson. 1982. Laboratoryacquired infections with hantaan virus, the etiologic agent of Korean hemorrhagic fever. J. Infect. Dis. 146:645-651. 96. LeFrancois, L., and D. S. Lyles. 1982. The interaction of antibody with the major surface glycoprotein of vesicular stomatitis virus. I. Analysis of neutralizing epitopes with monoclonal antibodies. Virology 121:157-167. 97. Legislative and Regulatory Front. 1995. Rabies vaccine for raccoons approved. J. Am. Vet. Med. Assoc. 207:680. 98. Leiby, D. A., C. H. Duggy, K. D. Murrell, and G. A. Schad. 1990. Trichinella spiralis in an agricultural in the rat population. J. ecosystem: transmission Parasitol. 76:360-364. 99. Ludlam, H., T. G. Wreghitt, S. Thornton, B. J. Thomson, N. J. Bishop, S. Coomber, and J. Cunniffe. 1997. Q fever in pregnancy. J. Infect. 34: 75-78. 100. Ludwig, S., W. M. Fitch, and C. Scholtissek. 1996. European swine virus as a possible source for the next influenza pandemic?, p. 520-524. In L. E. Brown, A. W. Hampson, and R. G. Webster (ed.), Options for the Control of Influenza III. Elsevier Science Publishers, Amsterdam, The Netherlands. 101. Markell, E., M. Voge, and D. T. John. 1992. Medical Parasitology, 7th ed. The W. B. Saunders Co., Philadelphia, Pa.

32

T. J. Marrie (ed.), Q Fever, vol. I. The Disease. CRC Press, Boca Raton, Fla. 104. Marrie, T. J. 1993. Q fever in pregnancy: report of two cases. Infect. Dis. Clin. Pratt. 2:207-209. 105. Marrie, T. J., H. and D. M. Waag. a risk factor for Canada. J. Infect.

Durant, J. C. Williams, E. Mintz, 1988. Exposure to parturient cats: acquisition of Q fever in maritime Dis. 158:101-108.

106. Marrie, T. J., D. Langille, V. Papukna, and L. Yates. 1989. Truckin’ pneumoniaan outbreak of Q fever in a truck repair plant probably due to aerosols from clothing contaminated by contact with newborn kittens. Epidemiol. Infect. 102:119-127. 107. McCaul, T. F. 1991. The developmental cycle of Coxiella burnetii, p. 223-235. In J. C. Williams and H. A. Thompson (ed.), Q Fever: the Biology of Coxiella burnetii. CRC Press, Boca Raton, Fla. 108. McCall, K. A., A. R. Gould, P. W. Selleck, P. T. Hopper, H. A. Westbury, and J. S. Smith. 1993. Polymerase chain reaction and other laboratory techniques in the diagnosis of long incubation rabies in Australia. Amt. Vet. J. 70:84-89. 109. McCormick, J. B., and S. P. Fisher-Hoch. 1994. Zoonoses caused by arenaviruses, p. 365-373. In G. W. Beran and J. H. Steele (ed.), Handbook of Zoonoses, Section B: Viral. 2nd ed. CRC Press, Boca Raton, Fla. 110. McCormick, J. B., and S. P. Fisher-Hoch. 1994. Zoonoses caused by Filoviridae, p. 375-384. In G. W. Beran and J. H. Steele (ed.), Handbook of Zoonoses, Section B: Viral, 2nd ed. CRC Press, Boca Raton, Fla. 111. McDade, J. E., and B. E. Anderson. 1996. Molecular epidemiology: applications of nucleic acid amplification and sequence analysis. Epidemiol. Rev. l&90-97. 112. McGivern, D., R. White, I. D. Paul, E. 0. Caul, A. P. C. H. Roome, and D. Westmoreland. 1988. Concomitant zoonotic infections with ovine chlamydia and ‘Q’ fever in pregnancy: clinical features, diagnosis, management and public health implications. Case report. Br. J. Obstet. Gynecol. 95: 294-298. 113. McKee, K. T., J. V. LeDuc, and C. J. Peters. 1991. Hantaviruses, p. 615-632. In R. B. Belshe (ed.), Textbook of Human Virology. Mosby Yearbook, St. Louis, MO. 114. Meehan, S. K. 1995. Concerns facing the profession: rabies epizootic in coyotes combated with oral vaccination program. J. Am. Vet. Med. Assoc. 206: 1097-1099.

102. Marrie, T. J. 1990. Acute Q fever, p. 125-160. In T. J. Marrie (ed.), Q Fever, vol. I. The Disease. CRC Press, Boca Raton, Fla.

115. Menna, A., R. Wittek, P. 0. Bachmann, A. Mayr, and R. Wyler. 1979. Physical characterization of a stomatitis papulosa virus genome: a cleavage map for the restriction endonucleases Hind111 and EcoRI. Virology 59:145-156.

103. Marrie,

116. Miller,

T. J. 1990. Q fever hepatitis, p. 171-177.

In

R. E. 1996. Xenotransplantation:

risks, clini-

CUMITECH

32

Diagnosis

cal potential, Dis. 2:64-70.

and future

prospects.

Emerg.

hfec.

117. Moos, A., and T. Hackstadt. 1987. Comparative virulence of intra- and interstrain lipopolysaccharide variants of Coxiella burnetii in the guinea pig model. Infect. Immun. 55:1144-1149. 118

119

Morse, S. S., and J. M. Hughes. 1996. Developing an integrated epidemiologic approach to emerging infectious diseases. Epidemiol. Rev. l&l-3. Morzunov, S. P., H. Feldmann, C. F. Spiropoulou, V. A. Semenova, I?. E. Rollin, T. G. Ksiazek, C. J. Peters, and S. T. Nichol. 1995. A newly recognized virus associated with a fatal case of hantavirus pulmonary syndrome in Louisiana. J. Virol. 69:19801983.

of Zoonotic

isolates from skunks in the United sis. University of Georgia, Athens.

Infections

37

States. M.S. the-

130. Ormsbee, R. A., and B. I? Marmion. 1990. Prevention of Coxiella burnetii infection: vaccines and guidelines for those at risk, p. 225-248. In T. J. Marrie (ed.), Q Fever, vol. 1, The Disease. CRC Press, Boca Raton, Fla. 131. O’Sullivan, J. D., A. M. Allworth, D. L. Patersen, T. M. Snow, R. Boots, L. J. Gleeson, A. R. Gold, A. D. Hyatt, and J. Bradfield. 1997. Fatal encephalitis due to novel paramyxovirus transmitted from horses. Lancet 349:93-95. 132. Palmer, S. R., L. Soulsby, and D. I. H. Simpson. 1998. Zoonoses: Biology, Clinical Practice and Public Health Control. Oxford University Press, New York, N.Y.

120. Murray, K., R. Rogers, L. Selvey, I?. Selleck, A. Hyatt, and A. Gould. 1995. A novel morbillivirus pneumonia of horses and its transmission to humans. Emerg. Infec. Dis. 1:31-33.

133. Patterson, W. C., L. 0. Mott, and E. Jenney. 1958. A study of vesicular stomatitis in man. J. Am. Vet. Med. Assoc. 19:57- 62.

121. Murray, K., I?. Selleck, I?. Hooper, A. Hyatt, A. Gould, L. Gleeson, H. Westbury, L. Hiley, L. Selvey, B. Rodwell, and I?. Ketterer. 1995. A morbillivirus that caused fatal disease in horses and humans. Science 268:94-97.

134. Peacock, M. G., R. N. Philip, J. C. Williams, and R. S. Faulkner. 1983. Serological evaluation of Q fever in humans: enhanced phase I titers of immunoglobulins G and A are diagnostic for Q fever endocarditis. Infect. Immun. 41:1089-1098.

122 . Nadin-Davis, S. A., G. A. Casey, and A. I. Wandeler. 1994. A molecular epidemiological study of rabies virus in central Ontario and western Quebec. J. Gen. Viral. 75:2575-2583.

135. Pearlman, E. S., and S. K. Ballas. 1994. False-positive human immunodeficiency virus screening test related to rabies vaccination. Arch. Pathol. Lab. Med. 118:805-806.

123. National Committee for Clinical Laboratory Standards. 1993. Procedures for the Recovery and Identification of Parasites from the Intestinal Tract. Proposed guideline M28-I?. National Committee for Clinical Laboratory Standards, Villanova, Pa.

136. Peters, C. J., P. B. Jahrling, and A. S. Khan. 1996. Patients infected with high-hazard viruses: scientific basis for infection control, p. 141-168. In T. F. Schwarz and G. Siegl (ed.), Imported Virus Infections. Springer-Verlag, Vienna, Austria.

124. Nawa, Y., J. Imai, K. Ogata, and K. Otsuka. 1989. The first record of a confirmed human case of Gnathostoma doloresi infection. J. Parasitol. 75: 166 169.

137. Pinsky, R. L., D. B. Fishbein, C. R. Greene, and K. F. Gensheimer. 1991. An outbreak of cat-associated Q fever in the United States. J. Infect. Dis. 164:202-204.

125. Nichol, S. T., C. F. Spiropoulou, S. Morzunov, I? E. Rollin, T. G. Ksiazek, H. Feldmann, A. Sanchez, J. Childs, S. Zaki, and C. J. Peters. 1993. Genetic identification of a hantavirus associated with an outbreak of acute respiratory illness. Science 262:914916.

138. Prasad, B. N., N. K. Chandiramani, and A. Wagle. 1986. Isolation of Coxiella burnetii from human sources. ht. J. Zoon. 13:112-l 17.

126. Nicholson, K. 1983. Human rabies, p. 6-23. In J. R. Pattison (ed.), Rabies: a Growing Threat. Van Nostrand Reinhold, Wokingham, England. 127. Nolte, K. B., R. M. Feddersen, K. Foucar, Zaki, F. T. Koster, D. Madar, T. L. Merlin, McFeeley, E. T. Umland, and R. E. Zumwalt. A pathological description of a disease caused new agent. Hum. Pathol. 26:110-120.

S. R. I?. J. 1995. by a

128. Nuzum, E. O., C. A. Rossi, E. H. Stephenson, and J. W. LeDuc. 1988. Aerosol transmission of hantaan and related viruses to laboratory rats. Am. J. Trap. Med. Hyg. 38:636-640. 129. Orciari,

L. A. 1995. Genetic analysis of rabies virus

139. Prince, H. N., D. L. Prince, and R. N. Prince. 1991. Principles of viral control and transmission, p. 411-444. In S. S. Block (ed.), Disinfection, Sterilization, and Preservation, 4th ed. Lea & Febiger, Philadelphia, Pa. 140. Raoult, D., A. Raza, and T. J. Marrie. 1990. Q fever endocarditis and other forms of chronic Q fever, p. 179-199. In T. J. Marrie (ed.), Q Fever, vol. I. The Disease. CRC Press, Boca Raton, Fla. 141. Reif, J. S. 1994. Vesicular stomatitis, p. 171-l 8 1. In G. W. Beran and J. H. Steele (ed.), Handbook of Zoonoses, Section B: Viral Zoonoses, 2nd ed. CRC Press, Boca Raton, Fla. 142. Reif, J. S., P. A. Webb, T. P. Monath, J. K. Emerson, J. D. Poland, G. E. Kemp, and G. Cholas. 1987. Epizootic vesicular stomatitis in Colorado, 1982. In-

Evermann

et al.

fection in occupational Med. Hyg. 36:177-182.

CUMITECH

risk groups.

Am. J. Pop.

143. Robinson, A. J., and D. J. Lyttle. 1992. Parapoxviruses: their biology and potential as recombinant vaccines, p. 285-289. In M. Binns and G. L. Smith (ed.), Recombinant Poxviruses. CRC Press, Boca Raton, Fla. 144. Robinson, A. J., and G. V. Petersen. 1983. Orf virus infection of workers in the meat industry. 2v. 2. Med. J. 96:81-85. 145. Rollin, I?. E., T. G. Ksiazek, L. H. Elliott, E. V. Ravkow, M. L. Martin, S. Morzunov, W. Livingstone, M. Monroe, G. Glass, and S. Ruo. 1995. Isolation of Black Creek Canal virus, a new hantavirus from Sigmodon hispidus in Florida. J. Med. Virol. 46:35-39. 146. Rupprecht, D. E., and J. S. Smith. 1994. Raccoon rabies- the re-emergence of an epizootic in a densely populated area. Semin. Viral. 5:155-164. 147. Schmaljohn, C. S., S. E. Hasty, J. M. Dahymple, J. W. LeDuc, H. W. Lee, C. H. von Bonsdorff, M. Brummer-Korvenkontio, A. Vaheri, T. F. Tsai, H. L. Regnery, D. Goldgaber, and I?. W. Lee. 1985. Antigenie and genetic properties of viruses linked to hemorrhagic fever with renal syndrome. Science 227:1041-1044. 148. Selvey, L. A., R. M. Wells, J. G. McCormack, A. J. Ansford, K. Murray, R. J. Rogers, I?. S. Lavercombe, P. Selleck, and J. W. Sheridan. 1995. Infection of humans and horses by a newly described morbillivirus. Med. J. Aust. 162:642-645. 149. Singh, S. B., and C. M. Lang. 1985. Q fever serologic surveillance program for sheep and goats at a research animal facility. Am. J. Vet. Res. 46:321325. 150. Slemons, R. D., and M. Brugh. 1994. Influenza, p. 385-395. In G. W. Beran and J. H. Steele (ed.), Handbook of Zoonosis, Section B: Viral, 2nd ed. CRC Press, Boca Raton, Fla. 151. Smith, J. S. 1988. Monoclonal antibody studies of rabies in insectivorous bats of the United States. Rev. Infect. Dis. lO:S637-S643. 152. Smith, J. S. 1989. Rabies virus epitopic variation: use in ecologic studies. Adv. Virus Res. 36:215-253. 153. Smith, J. S. 1996. New aspects of rabies with emphasis on epidemiology, diagnosis, and prevention of the disease in the United States. Clin. Microbial. 9:166-176. 154. Smith, J. S., D. B. Fishbein, C. E. Rupprecht, and K. Clark. 1991. Unexplained rabies in three immigrants in the United States. A virologic investigation. N. Engl. J. Med. 324:205-211. 155. Smith, J. S., L. A. Orciari, and P. A. Yager. 1995. Molecular epidemiology of rabies in the United States. Semin. Viral. 6:387-400. 156. Tabel,

H., A. H. Corner, W. A. Webster,

and C. A.

Casey. 1974. History and epizootiology Canada. Can. Vet. J. 15:271-281.

32

of rabies in

157. Taubenberger, J. K., A. H. Reid, A. E. Krafft, K. E. Bijwaard, and T. G. Fanning. 1997. Initial genetic characterization of the 1918 “Spanish” influenza virus. Science 275:1793-1796. 158. Torrez-Martinez, N., and B. Hjelle. 1995. Enzootic of Bayou hantavirus in rice rats (Oryzomys palustris) in 1983. Lancet 346:780-781. (Letter.) 159. Truyen, V., C. R. Parrish, T. C. Harder, and 0. R. Kaaden. 1995. There is nothing permanent except change. The emergence of new virus diseases. Vet. Microbial. 43:103-122. 160. Tsai, T. F. 1987. Hemorrhagic fever with renal syndrome: mode of transmission to humans. Lab. Anim. Sci. 37~428 -430. 161. Uhaa, I. J., V. M. Dato, F. E. Sorhage, J. W. Beckley, D. E. Roscoe, R. D. Gorsky, and D. B. Fishbein. 1992. Benefits and costs of using an orally absorbed vaccine to control rabies in raccoons. J. Am. Vet. Med. Assoc. 201:1873-1882. 162. Umenai, T. H., W. Lee, I?. W. Lee, T. Saito, T. Toyoda, M. Hongo, K. Yoshinaga, T. Nobunaga, T. Horiuchi, and N. Ishida. 1979. Korean hemorrhagic fever in staff in an animal laboratory. Lancet i:314316. 163. Waag, D., J. Chulay, T. Marrie, M. England, and J. Williams. 1995. Validation of an enzyme immunoassay for serodiagnosis of acute Q fever. Eur. J. Clin. Microbial. Infect. Dis. 14:421-427. 164. Walton, T. E., P. A. Webb, W. L. Kramer, G. C. Smith, T. Davis, F. R. Holbrook, C. G. Moore, T. J. Schiefer, R. H. Jones, and G. C. Janney. 1987. Epizootic vesicular stomatitis in Colorado, 1982. Epidemiologic and entomologic studies. Am. J. Trap. Med. Hyg. 36:166-176. 165. Washington State Department of Health Workshop on Rabies. 10 October 1995. Richland, Wash. 166. Webb, I?. A., T. P. Monath, J. S. Reif, G. C. Smith, G. E. Kemp, J. S. Lazuick, and T. E. Walton. 1987. Epizootic vesicular stomatitis in Colorado, 1982. Epidemiologic studies along the northern Colorado front range. Am. J. Trap. Med. Hyg. 363183-188. 167. Webster, R. G. 1993. Influenza, p. 37-45. In S. S. Morse (ed.), Emerging Viruses. Oxford University Press, Oxford, United Kingdom. 168. Wedum, A. G., W. E. Barkley, and A. Hellman. 1972. Handling of infectious agents. J. Am. Vet. Med. Assoc. 161:1557-1567. 169. Wells, R. M., S. S. Estani, 2. E. Yadon, D. Enria, R. Padula, N. Pini, J. N. Mills, C. J. Peters, E. L. Segura, and the Hantavirus Pulmonary Syndrome Study Group for Patagonia. 1997. An unusual hantavirus outbreak in southern Argentina: person-toperson transmission? Emerg. Infect. Dis. 3:171-174.

CUMITECH

32

170. Williams, J. C., G. Peacock, D. M. Waag, G. Kent, M. I. England, G. Nelson, and E. H. Stephenson. 1992. Vaccines against coxiellosis and Q fever: development of a chloroform:methanol residue subunit of phase I Coxiella burnetii for the immunization of animals. Ann. N. Y. Acad. Sci. 653:88-93. 171. Williams, J. C., and V. Sanchez. 1994. Q fever and coxiellosis, p. 429-446. In G. W. Beran and J. H. Steele (ed.), Handbook of Zoonoses, Section A, 2nd ed. CRC Press, Boca Raton, Fla. 172. Winkler, W. G., and S. R. Jenkins. 1991. Raccoon rabies, p. 325-340. In G. M. Baer (ed.), The Natural History of Rabies, 2nd ed. CRC Press, Boca Raton, Fla.

Diagnosis

of Zoonotic

Murphy, C. M. Fauquet, Ghabrial, A. W. Jarvis, G. and M. D. Summers (ed.), cation and Nomenclature lag, New York, N.Y.

Infections

39

D. H. L. Bishop, S. A. P. Martelli, M. A. Mayo, Virus Taxonomy: Classifiof Viruses. Springer-Ver-

175. Yanagihara, R., and D. J. Silverman. 1990. Experimental infection of human vascular endothelial cells by pathogenic and nonpathogenic hantaviruses. Arch. Virol. 111:281-286. 176. Yeaman, M. R., and 0. G. Baca. 1990. Antibiotic susceptibility of Coxiella burnetii, p. 213-223. ha T. J. Marrie (ed.), Q Fever, vol. I. The Disease. CRC Press, Boca Raton, Fla.

173. Worswick, D., and B. P. Marmion. 1985. Antibody responses in acute and chronic Q fever and in subjects vaccinated against Q fever. J. Med. Microbial. 19:281-284.

177. Young, P. L., K. Halpin, P. W. Selleck, H. Field, J. L. Gravel, M. A. Kelly, and J. S. MacKenzie. 1996. Serologic evidence for the presence in Pteropus bats of a paramyxovirus related to equine morbillivirus. Emerg. Infect. Dis. 2~239-240.

174. Wunner, W. H., C. H. Calisher, R. G. Dietzgen, A. 0. Jackson, E. W. Kitajima, M. Lafon, J. C. Leong, S. Nichol, D. Peters, J. S. Smith, and P. J. Walker. 1996. Rhabdoviridae, p. 275-288. In F. A.

178. Yuill, T. M. 1980. Vesicular stomatitis, p. 125-143. In J. H. Steele and G. W. Beran (ed.), Handbook Series in Zoonoses, Section B: Viral Zoonoses, vol. I. CRC Press, Boca Raton, Fla.