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Last updated January 1, 2014

Zoonoses of House Pets Other Than Dogs, Cats and Birds

Bruno B. Chomel, DVM PhD. Pediatric Infectious Diseases Journal, 1992, 11:479-487

The objective is not to cover every species that can be used as pets and every disease, especially the rare arid exotic ones that they can transmit to us, but rather to focus on the most common "other house pets" and the potential health threats that they can represent. Some zoonoses are quite common as salmonellosis or campylobacteriosis but are usually not life-threatening. On the other hand some zoonoses are rather uncommon but can be particularly severe for infected persons, such as lymphocytic choriomeningitis (LCM) or rabies. Some zoonoses are described in more details than other ones, although they are less common, because outbreaks associated with house pets have been well-documented.

If one excludes gastrointestinal infections such as salmonellosis or yersiniosis, most zoonoses described in this paper are rare events associated with pet ownership.

Pet Rabbits and Rodents
Zoonoses transmitted by pet rabbits and rodents are quite rare (Table 1). Most of the health problems encountered with these animals are related to allergies or bites. A distinction should be made between the domestic pets (rabbits, guinea pigs, hamsters, mice or rats) and wild rodents kept as pets. Although the first group is rarely involved in transmitting zoonoses, a special warning should be made for wild animals; for example, woodchucks could transmit rabies and squirrels can transmit tularemia, rat bite fever or leptospirosis. As a general rule wildlife should not be kept as pets because of the health risk. Any wild animal should be handled with caution and referred to wildlife specialists.

Although many rodents can potentially transmit many infectious organisms, lagomorphs (which include rabbits) are rather safe pets, most of the health problems encountered being allergies. Among them the domestic or European rabbit is certainly an excellent pet for children.

Rabbit
Diseases of major public health importance in domestic rabbits are rarely encountered. Biting is uncommon but rabbits can inflict painful scratches with their rear limbs if improperly restrained.[3] Among the infectious diseases Pasteurella multocida may cause cutaneous infection in humans.[4] Other diseases to which rabbits are susceptible, e.g. salmonellosis, yersiniosis, tularemia, are extremely rare and are more commonly transmitted to humans by wild animals. Direct zoonotic transmission of Yersinia pseudotuberculosis from domestic rabbits has been documented.[5] More commonly some external parasites of the rabbit including fur mite acariasis (Cheyletiella) and dermatophytosis (Trichophyton) may be transmitted to humans.

Cheyletiella infestation (rabbit fur mite).
The rabbit fur mite, Cheyletiella parasitivorax, is uncommon in the domestic rabbit. It is an external parasite of the skin and hair that does not excavate tunnels or furrows in the skin. The life cycle is completed in about 35 days. Adult females and eggs can survive for 10 days off the animal body, but the larvae, nymphs and adult males are not very resistant and die in about 2 days in the environment.[6] Lesions in rabbits involve hair loss and a mild scaly, oily dermatitis. In humans the disease consists of a papular, and pruritic eruption on the arms, thorax, waist and thighs. Human infestation is transitory, inasmuch as the mites do not reproduce on human skin. For prevention of human infestation the infested rabbits should be treated with insecticides such as methyl carbamate once a week for 3 to 4 weeks.

Fungal skin infections (ringworm).
Fungal skin infections caused by Trichophyton mentagrophytes are rare. In rabbits irritation and inflammation of skin areas occur with crusts, scabs and hair loss. Affected animals should be isolated. Antifungal treatment with topical antifungal agents or systemic griseofulvin (25 mg/kg) for 4 weeks is effective. The spectrum of ringworm in humans varies from subclinical colonization to an inflammatory scaly eruption that spreads peripherally and causes localized alopecia. Diagnosis is made by identifying hyphae in skin scrapings on a potassium hydroxide slide or by isolation in fungal culture media, the only method that allows identifi-cation of the species. In humans topical treatment with clotrimazole (Lotrimin®, Mycelex®) or miconazole (Monistat-derm®), twice a day for 2 to 4 weeks, is usually sufficient. When extensive lesions are observed or scalp ringworm (tinea capitis), oral griseo-fulvin (Fulvicin®, Grifulvin V®, Grisactin®) should be used. In adults the dosage is 500 mg twice a day for 4 weeks at least.[7] In children the usual dose of oral microcrystalline griseofulvin is 10 to 15 mg/kg (up to 500 mg), given in one or two doses, preferably with fatty food such as ice cream or whole milk. Treatment should be continued for 4 to 8 weeks.

Rodents
Although rodents, especially mice and rats, are definitively associated with transmission of major fatal diseases to humans, such as plague, typhus and leptospirosis, they can be very good pets. The albino rat, domestic variety of the brown rat (Rattus norvegicus) and the albino domestic mouse (Mus musculus) are kept by many people. However, guinea pigs hamsters and gerbils are the most common house pets among the rodent group.

As mentioned by Wagner and Farrar,[8] the most important concerns about rodents for pet owners are bites and allergies. Human allergies to rodent dander are common. Symptoms are characterized by cutaneous (reddening, itching, hives) and respiratory problems. Infectious diseases from pet rodents are rare events. Among those, salmonellosis and lymphocytic choriomeningitis are of major concern.

Salmonellosis.
Guinea pigs are highly susceptible to Salmonella infection and develop severe clinical disease (septicemia). In guinea pigs, high mortality is the rule. Fish et al.[9] have reported a family outbreak of salmonellosis due to contact with guinea pigs, raised a commercial ranch in Canada. Mice and rats are so very susceptible and may carry subclinical infections for long periods. These infections are usually used by Salmonella enteritidis bio typhimurium. If salmonellosis occurs in a child who has a rodent pet, the pet's feces should be cultured for Salmonella. Negtive cultures may occur because shedding may be only intermittent.

Lymphocytic choriorneningitis.
LCM virus is found many rodent species and spreads to humans through contact with infected aerosols, direct animal contact or rodent bites. The natural reservoir of the disease is the domestic mouse (M. musculus), which usually is asymptomatic.[3, 6, 7, 10]

The LCM virus (an RNA virus of the arenaviridae family) is transmitted among rodents horizontally through secretions (urine, saliva, feces) and vertically the embryos, especially in mice. Infected offspring develop a persistent infection and shed the virus during most of their lifespan. Outbreaks have been reported in laboratory mice, and human cases occurred in houses where infected mice were caught. In man the disease is sporadic, but outbreaks may occasionally occur. Such outbreaks of LCM occurred in the late 1960s and early 1970s in Germany and in the United States, associated with the use of hamsters as pets. In Germany 47 human cases associated with pet hamsters were reported within a 2-year period.[11] In the United States a nationwide epidemic occurred in late 1973 and early 1974 totaling at least 181 cases in 12 states with 57 cases in New York State[12] and in California. All were associated with pet hamsters from single breeder in Birmingham, AL. This breeder was an employee of a biologic products firm whose tumor cell lines were found to be positive for LCM. This same cell source was also incriminated in a prior outbreak at the University of Rochester Medical Center, Rochester, NY.[13] Since the suspension of sale of pet hamsters by the Birmingham breeder and of the distribution of positive tumor cell lines by the biologic products firm, no further outbreaks have been reported in the United States.

In hamsters LCM virus infection can be detected only by laboratory tests.[14] In humans the course of infection varies from clinically inapparent to a flu-like infection with fever, headache and severe myalgia, occurring 5 to 10 days after infection. Very few patients progress to aseptic meningitis, which is characterized by a very high lymphocyte count in the cerebrospinal fluid. On rare occasions there may be meningoencephalitis. Chronic sequelae are not com-mon and fatal cases are rare.[6]

Diagnosis of infection in humans is based on viral isolation from blood, nasopharynx or cerebrospinal fluid samples taken early in the attack and inoculated onto tissue cultures or injected intracerebrally into LCM-free adult mice.

Indirect immunofluorescence test or rising titers of complement fixation antibodies (which appear during the first or second week of the disease) on paired sera reveal a recent infection. Serum neutralization tests can also be used to detect recent evidence of infection. Because the disease is self-limiting, treatment in humans is for symptomatic relief only.

Dermatophytosis.
Tinea favus of rats and mice, caused by Trichophyton quinckeanum, is widespread.[3] In laboratory mice and guinea pigs, infection is mainly caused by T. mentagrophytes. The lesion, localized on the head or trunk, is white and scabby; but rodents often have no noticeable lesions. The infection is transmitted to humans and dogs. (For diagnosis and treatment see specific paragraph in zoonoses of rabbit).

Bites (pasteurellosis, rat bite fever, tularemia and rabies).

Pasteurellosis.
Among bite-transmitted zoonoses, infection by P. multocida (transmission of P. multocida from rodents to humans may occur without bite; however, it is certainly the principal mode of transmission) is certainly the most common with domestic pets. If most of the cases occur from cat and dog bites, nevertheless rodents harbor P. multocida in their oral cavity and can at times transmit the orga-nism through a bite wound. P. multocida is likely to be the pathogen if cellulitis develops within a few hours after the bite. Swelling, reddening and intense pain in the region are the main signs and symptoms. If the incubation period is longer staphylococcal or streptococcal infection is more likely. Although penicillin is likely to be effective in cases of pasteurellosis, cultures should always be obtained from infected wounds to determine the most appropriate antibiotic therapy. Treatment of bites in humans should be started with medication adequate to cover staphylo-coccal, streptococcal, pasteurella and anaerobic infections. Therapy in children may be started with amoxicillin/clavulanate potassium (Augmentin®), 40 mg/kg/day in three equal doses (up to 500 mg each) for 7 to 10 days. Alternatively a less ideal therapy can be started with a combination of penicillin and a cephalosporin (such as cephalexin (Keflex®), at a dosage of 50 mg/kg/day in four divided doses (up to 500 mg. each).

Rat-bite fever (Sodoku, Haverhill fever).
Rat-bite fever (REF) is a rare disease that can be transmitted by rats, which are healthy carriers of Streptobacillus moniliformis or Spirillum minus) in their nasopharynx.

Streptobacillary RBF is a rare disease in the United States. Of 14 cases of rat-bite fever on record since 1958, 7 originated from the bite of laboratory rats.[15,16] Bites by wild rodents (rats, squirrels) can also transmit the infectious agent.[16] Arkless[17] described infection caused by the bite of a pet mouse. Infection has also followed consumption of contaminated raw milk.[15] Streptobacillary RBF has an incubation period of 3 to 10 days, a rapidly healing point of inoculation and abrupt onset of irregularly relapsing fever, shaking chills, vomiting, headache, arthralgia, myalgia and regional lymphadenopathy. Shortly after onset a maculopapular rash appears on the extremities. Endocarditis is a possible complication. Diagnosis of rat-bite fever is made by culture of the organism from blood or joint fluid.[7] Recommended therapy in humans for RBF is penicillin (parenteral procaine penicillin G 600 000 units twice daily for 7 days). Alternatively streptomycin or tetracycline can be used.[16]

Spirillary RBF is even rarer and has an incubation period of 1 to 6 weeks. Clinically S. minus differs from streptobacillary fever in the rarity of arthritic symptoms, a distinctive rash and a common reactivation of the healed wound when symptoms appear.[18]

Tularemia.
Tularemia, also known as "rabbit fever" is an acute febrile illness caused by Francisella tularensis. Rodents are very susceptible to the disease that usually causes a fatal septicemia. Because the disease is mainly transmitted by ticks and fleas from rodent to rodent, pet rabbits or rodents should not be a major risk for transmission of tularemia. There have been documented cases of transmission from domestic cats and more recently from the bite of a squirrel kept as a household pet which died minutes after biting the child.[19] The commonly accepted drug of choice for treatment of tularemia in humans is streptomycin at 30 to 40 mg/kg daily by intramuscular route divided every 12 hours for 7 days.[20]

Rabies.
Although bites from pet rodents are frequent events, no human case of rabies has ever been reported from bites by pet rodents. However, one should be very careful any time a wild rodent kept as a pet has bitten a person. Cases of rabies have been reported in woodchucks, squirrels and even in a rat.[21]

Yersiniosis.
Infections caused by Y. pseudotuberculosis and Yersinia enterocolitica may be contracted from pet rodents. Guinea pigs are very commonly infected with Y. pseudotuberculosis.[.22] The course of the disease in these animals is usually subacute. Loss of weight and diarrhea are often the only clinical signs. Healthy carriers are common. In rats and mice the infection is common but usually without clinical signs. Children can be infected by fecal-oral contamination on very rare oc-casions. In humans the disease is mainly observed in children, adolescents and young adults. The most common clinical form, after 1 to 3 weeks of incubation, is mesenteric adenitis, or pseudoappendicitis, with acute abdominal pain in the right iliac fossa, fever and vomiting. The disease is usually more common in young males. Diagnosis requires the isolation and identification of the etiologic agent. Serologic tests such as enzyme-linked immunosorbent assay are also available. When the disease is mild (uncomplicated pseudoappendicular syndrome) antimicrobial chemo-therapy is not useful.[23] Y. pseudotuberculosis is usually susceptible to aminoglycosides, trimethoprim-sulfa-methoxazole or tetracycline.[18]

Y. enterocolitica is also found in rodents, which are usually healthy carriers.[24] Chinchillas are very susceptible to the infection and several epizootics occurred in Europe and the United States.[6] Guinea pigs also are commonly infected by Y. enterocolitica. The usual serotypes found in rodents do not affect humans in humans Y. enterocolitica affects mainly young children. The major symptoms are an acute enteritis with watery and sometimes bloody diarrhea, of 3 to 14 days duration, and abdominal pain. Diagnosis is based on isolation of the agent from feces of patients. An enzyme-linked immunosorbent assay on paired sera is also useful to determine infection. Aminoglycosides and trimethoprim-sulfamethoxazole are the most appropriate antibiotics.[19]

Campylobacteriosis.
Campylobacter infection can occur in some rodent species. Proliferative ileitis, a specific enteric syndrome of hamsters, is probably caused by a strain of Campylobacter spp. Hamsters certainly represent a potential source of human infection, but no hamster-associated cases have been reported to date.[10] In humans Campylobacter infection is characterized by diarrhea, abdominal pain, cramps, fever and vomiting. The diarrhea is frequently bloody. The incubation period is 2 to 5 days, and the disease usually does not last for more than a week. Treatment is usually limited to fluid replacement therapy, although if one suspects the infection on clinical or epidemiologic grounds, an early treatment with erythromycin will reduce the period of excretion of the organism and will shorten the duration of symptoms.

Some other rare infectious diseases.

Plague.
Plague is an endemic disease in many wild rodents in the Western United States. Several human cases have been associated with pets, especially cats,[25] but there are no literature reports of transmission to humans from pet rodents.

Leptospirosis.
Although rodents, especially rats, are known to harbor and shed for long period of time various Leptospira interrogans serovars, very few cases of human infection from pet rodents has been reported. In one instance L. interrogans serovar ballum was contracted from a pet mouse.[26] Outbreaks in personnels working with laboratory rats and mice have keen documented in Europe and in the United States.[5]

Hemorrhagic fever with renal syndrome or Korean hemorrhagic fever.
This is a group of rodent-borne viral diseases (Hantaan virus) that are endemic or occur as focal epidemics on the Eurasian continent and Japan. In general Hantaan virus isolates from Asia are considered more pathogenic to humans than European and North American strains. Wild rodents in rural areas or wild rats in cities[27] are the reservoir of the virus that they can shed for several weeks. Several outbreaks have been reported in Japan and Europe in laboratory personnel[28] infected by laboratory rats. Hantaan viruses cause chronic, apparently asymptomatic, infections of their rodent hosts, but associated human cases may reveal the animal infection. The disease in laboratory personnel has been characterized by fever and a "flu-like" syndrome, with fever, myalgia and few days later oliguria, proteinuria and hematuria. No fatal case has been associated with laboratory-acquired infection. Usually patients will recover without sequelae. Infection is contracted by handling infected animals or from contaminated aerosols. Most laboratory rat suppliers use a screening test and destroy infected colonies. The diagnosis of infection is based on viral isolation and more often on serodiagnosis by indirect immunofluorescence or enzyme-linked immunosorbent assay.

Cestodiasis (tapeworm).
Cestodes or tapeworms infect a wide range of species including rabbits and rodents. Hymenolepis nana, the dwarf tapeworm, is found in rodents, especially hamsters. Hymenolepis diminuta is the rat tapeworm but may also be found in other rodents. Hymenolepiasis occurs primarily in children. Usually the infection is asymptomatic in humans, but if parasites are present in large numbers, gastrointestinal disorders such as abdominal pain, nausea, vomiting and diarrhea may occur. Eggs of some Hymenolepis spp. are infective to the definitive host when passed in the feces. Infection in humans from infected rodents may be acquired either by ingestion of eggs from fecally contaminated fingers or from contaminated food or water. When eggs of the directly transmitted Hymenolepis spp. are ingested, they hatch the intestine, liberating an oncosphere that enters mucosal villus and develops into a cysticercoid larva within 5 days. The cysticercoid ruptures the villus, migrates into the lumen and attaches to the lower small intestine. It reaches the adult phase in 2 weeks and starts to release eggs. Diagnosis of infection is made by microscopic identification of the eggs in the feces. One dose of praziquantel (Biltricide®) at 25 mg/ kg or niclosamide (Yomesan®, Niclocide®) for a week are effective for.. treatment of hymenolepis infection[3, 4, 6, 18] in humans.

Acariasis (Trixacarus caviae).
Several external parasites can infest rodents. Among those, Trixacarus caviae, a parasite mainly found in guinea pigs, can be transmitted to humans. In guinea pigs the infection is usually asymptomatic. Stress and/or poor care can lead to severe alopecia, dermatitis and pruritus on the body and legs, with the skin being thickened, dry and scaly. In humans, pruritic skin lesions on the hands, arms or neck can be observed in children. Diagnosis may be established by recovering the mite from its burrow and identifying it microscopically. Treatment of infected children with crotamiton (Eurax®) in one application per day for 2 to 5 days is the most common treatment, or lindane (1% gamma-benzene hexachlo-ride (Kwell®)).[3, 18]

Turtles, Lizards, Snakes and Aquarium Fish
Today reptiles are commonplace pets, residing in approximately 453,000 households in the United States. One of every 200 households has turtles, lizards, snakes or crocodiles as pets (Table 2).[29]

Salmonellosis.
Salmonellosis is certainly the most frequent and major zoonosis transmitted by reptiles, especially turtles.[30, 31] Of all zoonoses, Salmonella infections present the most significant hazard to children, as they are at greater risk of disease than are adults, because children and animals are frequently in close contact with each other, and handwashing prac-tices in children are often not well-developed.[32]

Pet turtles have been recognized as a major source of human salmonellosis since Hershey and Mason isolated Salmonella hartford from the pet turtle of a 7-month-old infant with Salmonella hartford gastroenteritis.[33] Subsequent investigations established that 14% of the estimated 2 million cases of human salmonellosis in the United States between 1970 and 1971 were linked to pet turtles, mainly the red eared turtle (Pseudemys scripta elegans).[34] With annual sales of 15 million turtles zoonotic salmonellosis was a growing problem. By 1975 commercial distribution of turtles less than 4 inches long was banned within the United States by the Food and Drug Administration. A 77% decrease in turtle-associated salmonellosis was noted after enactment.[35, 36] Nevertheless an estimated 3 to 4 million turtles are shipped annually from the United States and sold all around the world. Several outbreaks have been reported in Japan,[37] Great Britain,[38, 39] Puerto Rico,[40] Israel,[41] and France.[42] Turtles are usually healthy carriers of Salmonella and shedding is very irregular, but they may shed Salmonella for up to 11 months.

The problem of Salmonella infection in turtles arises from the widespread contamination and persistence of the microorganism in turtle-breeding ponds and nesting areas. Turtles can acquire the organism in ovo or after hatching.[43] Use of antibiotics for attempted control of Salmonella in pet turtle husbandry has been widely practiced. In their attempt to eradicate Salmonella with gentamicin sulfate, turtle farmers have created an even greater health hazard through selection of antibiotic-resistant strains.[44] Treatment of pet turtles is not recommended and infected reptiles should be destroyed. However, knowledge of the potential health hazards, along with proper sanitation, is usually sufficient to prevent human infection, Pet turtles should not be displayed in classrooms where children can handle them or have contact with their container. Identification of the microorganism from stool culture and an antibiogram should be performed when salmonellosis is suspected. Similarly culture should be performed from the pet reptile or from its aquarium. In humans primary treatment of salmonellosis consists of fluid and electrolyte replacement. Antibiotics are not recommended, except in severe forms, because they not only fail to shorten the duration of the illness but also may prolong the carrier state.

Salmonella infection can be acquired not only from pet turtles but also from other reptiles such as lizards or snakes,[45] from frogs[46] or aquarium fish.[47]

Other gastrointestinal bacterial infections.

Edwardsiella.
Human infection with Edwardsiella tarda is uncommon. This organism can be found in cold blooded animals, reptiles and fish (goldfish, cat-fish, bass). In humans the organism may cause gastroenteritis resembling Salmonella infections. At least one case was reported in the United States, associated with a pet turtle.[48]

Plesiomonas.
Plesiomonas shigelloides is a Gram-negative rod that causes progressive ulcerative stomatitis in snakes ("mouth-rot disease"). It may cause gastroenteritis in humans. A case of acute gastroenteritis has been reported from a zoo animal keeper infected after handling a sick boa constrictor.[49] These organisms can also been found in fish tanks. Diagnosis is made by stool culture. In humans treatment with trimethoprim-sulfamethoxazole (Bactrim®, Septra®) for 5 days is usually effective.

Yersiniosis.
Yersinia enterocolitica has been found in water on cold blooded animals such as frogs and fish[50, 51] and could be potentially transmissible to humans. However, the serotypes involved are not usually found in humans.

In the United States more than 20 million house-hold aquariums are maintained, accommodating an annual sale of approximately 600 million pet fish[52] mostly coming from foreign countries (southeast Asia. South America) and from Florida. However, very few cases of zoonoses are reported, and no major outbreaks of human disease for which diseased fish were directIv responsible have been recently reported.[52] Among the bacterial diseases, mycobacteriosis is certainly of major concern.

Mycobacteriosis
Mycobacterial infections are certainly among the major zoonoses that can be transmitted by aquarium fish.[53, 54] Mycobacterium marinum, Mycobacterium fortuitum and Mycobacterium platypolcitis have been associated with fish and human disease for many years. Skin ulcers caused by Mycobacterium marinum, contracted from fish tanks, have been reported. In two cases a cut in the hand had preceded the cleaning of a home fish aquarium.[55] In-fection by Mycobacterium marinum, also known as "swimming pool granuloma," is characterized after several weeks of incubation by papular lesions, usually on the fingers or hands that evolve to dark suppurative lesions. In infected fish granulomatous lesions are usually observed. A diagnosis can be made by isolating and identifying the organism. Infected fish should be destroyed and the aquarium should be disinfected (5cc calcium hypochlorite solution) before other fish are added.[56] In humans infection is often self-limited. If the lesion persists or spreads treatment with minocycline (Minosin®), 100 mg twice daily for 6 to 8 weeks, is appropriate.[7] However, minocycline should not be used for children less than 9 years old. Use of rifampin (Rifadin®, Rimactane®) has also been very successful,[57] usually in association with ethambutol and trimethoprim-sulfamethoxazole.

Melioidosis and exotic fish
Melioidosis is an uncommon disease in humans with a wide range of clinical manifestations from inapparent infection to a rapid fatal septicemia. Pseudomonas pseudomallei, the infectious agent, is endemic in southeast Asia. where it is saprophytic in certain soils and waters. Recent studies have shown that the water of tanks in which exotic aquarium fishes were imported was contaminated with this bacillus (A Dodin, personal communication). Disinfection of aquariums with bleach between water changes should be recommended in pet stores to prevent spread of infection.

Erysipelothrix infection
Erysipelothrix insidiosa (or rhusiopathiae) has been reported in humans contaminated by handling fish. It is mainly an occupational disease affecting fishermen. The organism ban be found on the surface of the fish and produces skin lesions in man known as "fish rose." Erysipelothrix infection is almost invariably introduced through minor skin wounds. Local erysipeloid most commonly occurs on the hands, and sometimes local lymphangitis and lymphadenitis may occur. Despite the potential of this organism to infect aquarium owners, no human cases have been reported from aquarium fish contamination. Penicillin is the appropriate treatment for erysipeloid.[59]

Pentostomiasis
Pentastomes (Armillifer sp.) are wormlike arthropods that are almost exclusively parasites of the reptilian respiratory system. Snakes are the definitive hosts and many wild rodents, on which snakes feed, are the intermediate hosts. The female parasite deposits eggs in the respiratory cavities of the reptiles. The eggs are expectorated or swallowed and then eliminated with the feces. Humans can be accidentaI hosts, by handling infected reptiles and placing contaminated hands to the mouth. In humans the infection is usually asymptomatic. The encapsulated larvae might be found during laparotomies or can be diagnosed by radiographic examination.[6, 60]

Ferrets
Among the large variety of house pets wild carnivores, especially ferrets, have experienced increasing popularity, with an estimated 6000 ferrets sold annually (Table 3).[61] According to the report of Ruprecht et al.,[62] there are currently 5 to 7 million pet ferrets in approximately 4 to 5 million households in the United States. Despite the fact that ferrets are enjoyable pets, much concern has been raised as a result of severe injuries to children by ferrets kept as use pets. The state of California, for example, does not allow ferrets or several other exotic animals as use pets.[61] As pets ferrets can also represent a health hazard by transmitting several disease agents to humans.

Rabies.
Like other carnivores ferrets are susceptible to rabies. In the United States rabies has been reported 13 times in ferrets since 1958, most often in pet ferrets acquired from pet shops.[63] Rabies immunization of ferrets with an inactivated vaccine has been shown to be effective for at least a year.[62] The United States Department of Agriculture granted approval on February 8, 1990, for the use of this vaccine in ferrets 3 months of age or older. Annual booster vaccinations are required. However, the Centers for Disease Control recommends that ferrets that have bitten humans be destroyed and their brains examined for rabies.

Influenza.
Ferrets are very susceptible to influenza viruses and have served for years as an animal model in the laboratory.[61, 63] In ferrets flu is characterized by sneezing, fever, lethargy, mucoserous nasal discharge, conjunctivitis and photophobia. The course of the influenza infection usually lasts less than a week. The disease can be severe in young ferrets. Human cases of influenza have occurred from contamination by aerosols from infected ferrets.[63] Similarly ferrets can be infected by humans shedding the virus.

Other potential zoonotic pathogens.
Ferrets can harbor several pathogenic microorganisms in their digestive tract, especially Salmonella and Campylobacter. In a 9-month survey of ferrets used in biomedical research, Salmonella was isolated from feces of 4% and Campylobacter jejuni/coli was isolated from feces of 18% of animals.[64] Although no human cases have been reported from ferret contamination, ferrets must be considered possible reservoirs for Campylobacter and Salmonella organisms. Ferrets should not be allowed to roam freely, and their feces should be discarded in a hygienic manner.[61] Ferrets can harbor many other zoonoses, including cryptosporidiosis, tuberculosis and listeriosis. They share parasites with dogs and cats (Toxocara, Dipylidium) as well as dermatophytosis (Microsporum canis, T. mentagrophytes). A complete description of these infections has been recently documented by Marini et al.[63]

Summary
In addition to dogs, cats and birds, which are the most frequent house pets, rabbits, rodents, fish and turtles are also vertebrate species that commonly share the home environment. Lizards, snakes and ferrets are less common pets. These species can transmit numerous diseases, especially to children who are more likely to be in close contact with them. The author presents a general review of zoonoses and potential zoonoses transmitted by rabbits, rodents and cold blooded vertebrates. Zoonoses transmitted by ferrets, a more recent popular house pet, are also considered. Although most zoonoses contracted from pets are relatively rare events, clinicians should be aware of any animal exposure, especially in immuno-compromised hosts. Because of the diversity and the large size of the pet population, exposure to animals should be systematically ascertained when examining a patient.

Addendum
Pet iguana-associated salmonellosis cases, which occurred in 1990 in two infants residing in Indiana, were recently reported (Morbidity and Mortality Weekly Report 1992;41:38-9). These cases emphasize the important role played by reptiles, particularly pet lizards, in the transmission of zoonoses. In both cases a rare Salmonella serotype Salmonella marina was involved, and there was no direct contact between the pet iguana and the infant. These two cases highlight that direct contact between the reptile and the infant is not necessary for transmission to occur.

Article Attachments:
Table 1: Zoonoses potentially transmitted by pet rabbits and rodents.
Table 2: Zoonoses potentially transmitted by reptiles and aquarium fish.
Table 3: Zoonoses potentially transmitted by ferrets.
References