Diseases Transmitted by Less Common House Pets

ABSTRACT Beside dogs and cats, the most common pets worldwide, an increasing number of pocket pets and exotic pets are making their way to more and more households, especially in North America and Europe. Although many of these animals make appropriate pets, they also can be a source of many zoonotic diseases, especially in young children and immunocompromised individuals. Some of these diseases can be life threatening, such as rabies, rat bite fever, and plague. Some others are quite common, because of the frequency of the pathogens harbored by these species, such as salmonellosis in reptiles and amphibians. Appropriate knowledge of the zoonotic agents carried by these “new” pet species is strongly recommended prior to acquiring pocket or exotic pets. Furthermore, adopting wildlife as pets is strongly discouraged, because it is always a risky action that can lead to major health issues.


INTRODUCTION
Many infectious diseases in humans can be acquired through contact with pets.Dogs and cats may be the most common pets around the world, but there are also many other vertebrates that share our household environment.
Although growth in pet ownership has leveled off in the past five years, more than 200 million pets of all kinds continue to enliven 65 million American households (Fig. 1).American pet owners live in the company of 116 million fish, birds, small animals, and reptiles.Fish tanks can be found in 7.2 million households and bird cages in 4.6 million households.Reptiles are pets in 1.8 million households.Pet rabbits are among the most common specialty and exotic pets, accounting for 3.2 million animals present in approximately 1.5% of U.S. households.Specialty or exotic pet ownership is 10.6%.It is estimated that between 1996 and 2001, the number of pet ferrets increased by 25.3%, with an estimated 1 million ferrets present in 0.5% of all households.A 12.6% increase in pet turtle ownership was also reported for the same time period.Similarly, the estimated number of households with reptiles doubled from approximately 850,000 to 1.7 million from 1991 to 2001.
The objective of this chapter is not to cover every species that can be kept as pets and every disease, especially the rare and exotic ones, that they can transmit to us but rather is to focus on the other most common "house pets" and the major health threats that they can represent.Only a brief discussion at the end of this chapter is devoted to more uncommon pets, especially ferrets and primates.However, because of the outbreak of monkeypox in prairie dogs and humans which occurred in the spring of 2003 in the United States, a few words are devoted to the risk of ownership of exotic pets.

PET RABBITS AND RODENTS
Zoonoses transmitted by pet rabbits and pet rodents are quite rare (Table 1).Most of the health problems encountered with these animals are related to allergies or bites.A major distinction should be made between domesticated pets (rabbits, guinea pigs, hamsters, mice, and rats) and wild or exotic rodents kept as pets.Although the first group is rarely involved in transmitting zoonoses, a special warning should be given for wild animals and exotic pets.As a general rule, wildlife and exotic animals should not be sold or kept as pets.Examples of potential zoonotic risks are that woodchucks may transmit rabies, since 42 wild woodchucks (Marmota monax) were diagnosed as rabid in 2012 in the United States, and squirrels may transmit tularemia, rat-bite fever (RBF), or leptospirosis.From 1995 through 2010, 737 rabid rodents and lagomorphs were reported to the Centers for Disease Control and Prevention (CDC), which represented a 62.3% increase compared with the number of rabid rodents and lagomorphs reported from 1979 through 1994.The most commonly reported rodents or lagomorphs were woodchucks, also known as groundhogs.All animals submitted to the CDC for additional viral characterization were positive for the raccoon rabies virus variant.Infectious virus or viral RNA was detected in salivary glands or oral cavity tissues in 11 of 13 rabid rodents.
However, a recent trend in pet ownership has emerged, especially in developed countries, namely, the purchase of exotic or nonconventional pets captured locally or imported from various parts of the world, where many zoonoses are endemic, or ownership of unconventional pets.This danger is well illustrated by an outbreak of tularemia which was identified among prairie dogs (Cynomys ludovicianus) at a commercial exotic animal distribution facility in Texas; approximately 250 of an estimated 3,600 prairie dogs caught in South Dakota and transported to Texas died at this facility.Potentially infected rodents were distributed to wholesalers, retailers, and individuals in several states or exported to Belgium, the Czech Republic, Japan, The Netherlands, and Thailand.An unusually high number of sick or dead prairie dogs were reported from Texas and the Czech Republic.Prairie dogs have been documented to be also infected with other human pathogens (e.g., Yersinia pestis, the agent of plague).In May 1998, a heavy die-off among prairie dogs at a Texan exotic animal retailer led to a positive diagnosis of plague in that colony.(Any wild animal should be handled with caution and referred to wildlife specialists.)The May 2003 outbreak of monkeypox in the mid-western United States is also a reminder that exotic pets can be a source of infection of native species in that they are highly susceptible to infections that they have never encountered before and can be a very effective source of human infection.A new bornavirus was recently identified and reported to be associated with the death from encephalitis of three variegated squirrel breeders in Germany, illustrating the importance of exotic animals as sources of new zoonoses.

Rabbits
The domestic or European rabbit (Oryctolagus cuniculus), which can be housed indoors or outdoors and fed a readily available pelleted feed, makes a good pet that can be house-trained.The rabbit is an excellent pet for children, because diseases of major public health importance are rarely encountered in domestic rabbits.Biting is uncommon, but rabbits can inflict painful scratches with their rear limbs if improperly restrained.

Infectious zoonoses
Among the organisms causing infectious diseases in rabbits, Pasteurella multocida may cause cutaneous infection in susceptible people, especially after a rabbit bite.Other diseases to which rabbits are susceptible, e.g., salmonellosis and tularemia, are extremely rare and are more commonly transmitted to humans by wild animals.
Cases of listeriosis have been reported to occur in farm rabbitries but do not seem to be of concern from pet rabbits.On the other hand, direct zoonotic transmission of Yersinia pseudotuberculosis infection from domestic rabbits has been documented.A study of pet rabbits in southern Italy investigated the presence of Encephalitozoon cuniculi antibodies.Overall, antibodies to E. cuniculi were found in 84 (67.2%) of the 125 pet rabbits tested.The results of that survey reinforced the assumption that rabbits may be the main reservoir of E. cuniculi; therefore, routine screening examinations of pet rabbits are strongly advised, considering the zoonotic potential of this parasite, especially in immunocompromised people.E. cuniculi infection should be considered in severely immunocompromised HIVinfected patients with multiorgan involvement and fever, especially when renal failure is present (Fig. 2).Microsporidial spores are usually seen in urine samples and in the involved organ.Albendazole therapy seems to be effective.
A few cases of endocarditis and lymphadenopathy caused by Bartonella alsatica have been reported in France from people raising rabbits.Cerebral larva migrans caused by Baylisascaris procyonis was reported to occur in pet rabbits infected by bedding straw contaminated with raccoon feces, but human contamination from these pets is very unlikely.Rabies and tuberculosis have infrequently been diagnosed in pet rabbits.For example, rabies virus infection (raccoon variant) was reported in 2005 in seven pet rabbits and one pet guinea pig in New York State, and postexposure treatment was required for several adults and children.These pets were caged outdoors unsupervised.More commonly, some external parasites of the rabbit may be transmitted to humans and cause infections, including fur mite (Cheyletiella parasitivorax) acariasis and dermatophytosis (Trichophyton mentagrophytes).

Cheyletiella (rabbit fur mite) infestation
The rabbit fur mite, C. 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 (Fig. 3).The life cycle is completed in about 35 days.Adult females and eggs can survive for 10 days off the animal's body, but the larvae, nymphs, and adult males are not very resistant and die in about 2 days in the environment.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, because the mites do not reproduce on human skin.In a recent human case, treatment with benzyl benzoate (Ascabiol) resolved all the patient's symptoms.To prevent human infestation, infested rabbits should be treated with insecticides (e.g., methyl carbamate) once a week for 3 to 4 weeks.

Dermatophytosis
Fungal skin infections (ringworm) due to T. mentagrophytes are relatively rare.A few cases related to rabbit exposure have been reported in the scientific literature.T. mentagrophytes is the most common dermatophyte in pet guinea pigs and rabbits; asymptomatic carriers are regularly seen in guinea pigs but not in rabbits.Two human cases of tinea corporis due to Arthroderma benhamiae (teleomorph of T. mentagrophytes) were described for the first time in Japan.The two people acquired the infection from their crossbred rabbit.Similarly, two cases of tinea gladiatorum due to T. mentagrophytes var.quinckeanum were described.A pet rabbit was probably the primary source of infection, which was then spread further by human-to-human contact to four other members of the same wrestling team, who were affected by tinea corporis.In rabbits, irritation and inflammation of skin areas occur, with crusts, scabs, and hair loss.Some rabbits (about 4%) are asymptomatic carriers.Affected animals should be isolated.Antifungal treatment with topical or systemic griseofulvin (25 mg/kg of body weight) 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 identification of the species.In humans, topical treatment with clotrimazole (Lotrimin or Mycelex) or miconazole (Monistat-derm) twice a day for 2 to 4 weeks is usually sufficient.Application of ketoconazole cream twice daily for 2 months was used for the two Japanese patients.When extensive lesions are observed, oral griseofulvin (Fulvicin, Grifulvin V, or Grisactin) should be used.For adults, the dosage is 500 mg twice a day for at least 4 weeks.For 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 to humans of major fatal diseases such as plague, typhus, and leptospirosis, they can be very good pets.The albino rat, the 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 rodents.It should be noted that introduction and ownership of gerbils are illegal in California.Furthermore, following the monkeypox outbreak in prairie dogs, restrictions on African rodents, prairie dogs, and certain other animals were recently set by the U.S. government.New World flying squirrels (mainly Glaucomys volans and Glaucomys sabrinus) have also gained some popularity as household pets, with an estimated 5,000 to 8,000 owners in the United States.
As mentioned by Wagner and Farrar, 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, and hives) and respiratory problems.
Zoonotic diseases from pet rodents are relatively rare.Among these, salmonellosis, lymphocytic choriomeningitis (LCM), and more recently, monkeypox virus infection are major concerns.Rodent-borne zoonotic diseases are discussed below.

Viral Zoonoses LCM
LCM virus (LCMV) is found in 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 does not present any symptoms.First described in 1933, LCM is a rodentborne zoonosis associated with the common house mouse (M.musculus).LCMV (an RNA virus of the family Arenaviridae) is transmitted horizontally among rodents through secretions (urine, saliva, and feces) and vertically to embryos, especially in mice.Infected offspring develop a persistent infection and shed the virus during most of their life spans.
Outbreaks have been reported to occur in laboratory mice, and cases have occurred in humans in houses where infected mice were caught.In humans, the disease is sporadic, but outbreaks may occasionally occur.Since 1960, several epidemics of LCMV infection involving at least 236 human cases have occurred in the United States.Such outbreaks of LCMV infection occurred in the late 1960s and early 1970s in Germany and the United States, related to the use of hamsters as pets.In Germany, 47 cases in humans associated with pet hamsters were reported within a 2-year period.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 and California.All were associated with pet hamsters from a single breeder in Birmingham, Alabama.This breeder was an employee of a biological-product firm whose tumor cell lines were found to be positive for LCMV.The same cell source was also incriminated in a prior outbreak at the University of Rochester Medical Center, Rochester, New York.In southern France, four human cases of acute meningitis due to LCMV occurred in 1993 after close contact with pet Syrian hamsters.An outbreak occurred in rodent breeding facilities in the United States in 2012.Of 97 employees tested, 31 (32%) had IgM and/or IgG to LCMV, and aseptic meningitis was diagnosed in 4 employees.Of 1,820 rodents tested in 1 facility, 382 (21%) mice (M.musculus) had detectable IgG, and 13 (0.7%) were positive by reverse transcription PCR; LCMV was isolated from 8. Rats (R. norvegicus) were not found to be infected.S-segment RNA sequence was similar to strains previously isolated in North America.
Several human cases, many of which were fatal, were also acquired in the past few years in the United States following organ transplantations.Viral sequences from the organ recipients were identical to those from the pet hamster acquired by the donor's household 17 days before organ donation.The hamster was traced back through a Rhode Island pet store to a distribution center in Ohio, and more LCMV-infected hamsters were discovered in both.Rodents from the Ohio facility and its parent facility in Arkansas were tested for the same LCMV strain as that involved in the transplantassociated deaths.Phylogenetic analysis of virus sequences linked the rodents from the Ohio facility to the Rhode Island pet store, the index hamster, and the transplant recipients.The seroprevalence of LCMV in rodents in surveys has been reported to be between 2.5% (California) and 21% (Washington, DC), but serology is not very reliable.In the investigation of a human case in Michigan, 22 (96%) of 23 mice captured were viremic but none were seropositive.Serologic studies conducted in urban areas of the United States have indicated that the prevalence of LCMV infection among humans is approximately 5%.Human-to-human transmission of LCMV has not been reported, except in a case of vertical transmission from an infected mother to her fetus.
In hamsters, LCMV infection is usually not associated with signs of illness and can be detected only by laboratory tests.In humans, the course of infection varies from being clinically unapparent to a flu-like infection, with fever, headache, and severe myalgia, occurring 5 to 10 days after infection.A small number of 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 common, and fatal cases are rare.
Diagnosis of infection in humans is based on isolation of the virus from the blood or from nasopharyngeal or cerebrospinal fluid samples taken early in the attack and inoculated onto tissue cultures or injected intracerebrally into LCMV-free adult mice.LCMV testing also includes assays such as immunohistochemistry, reverse-transcription PCR, and TaqMan real-time PRC.Serodiagnostic tests include enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence assay, and immunoglobulin G (IgG) Western blotting.Serum screening is performed by indirect immunofluorescence assay and titration of IgM and IgG antibodies by ELISA.Since the disease is self-limiting, treatment is for symptomatic relief only.

Monkeypox
The first outbreak of human monkeypox infection in the Western Hemisphere began in May 2003 in the mid-western United States and was attributed to contact with infected exotic pets.Seventy-one suspected cases of monkeypox were investigated, primarily in Wisconsin, Indiana, and Illinois.Most of the affected people reported close contact with ill prairie dogs, although at least one case is thought to be related to an ill rabbit (which had contact with a sick prairie dog).No patients have been confirmed to have had exposure to people with monkeypox as their only possible exposure.In a follow-up study, case patients were more likely than controls to have had daily exposure to a sick animal (odds ratio [OR] 4.0; 95% confidence interval [CI], 1.2 to 13.4), to have cleaned cages or removed bedding of a sick animal (OR, 5.3; 95% CI, 1.4 to 20.7), or to have touched a sick animal (OR, 4.0; 95% CI, 1.2 to 13.4).These findings showed that human infection was associated with handling of monkeypox virus-infected animals and suggested that exposure to excretions and secretions of infected animals can result in infection.Prairie dogs appear to have been infected through contact with Gambian giant rats and dormice that originated in Ghana.Trace-back investigations to identify the source of introduction of monkeypox into the United States identified a Texas animal distributor who had imported a shipment of approximately 800 small mammals from Ghana on 9 April 2003 that contained 762 African rodents, including rope squirrels (Funisciurus spp.), tree squirrels (Heliosciurus spp.), Gambian giant rats (Cricetomys spp.), brush-tailed porcupines (Atherurus spp.), dormice (Graphiurus spp.), and striped mice (Hybomys spp.).The U.S. Department of Health and Human Services issued an embargo order on the import of rodents from Africa, effective 11 June 2003.In addition, the U.S. Department of Health and Human Services has also prohibited the distribution, sale, transport, or intentional release into the wild of prairie dogs and six African rodent species.
In humans, the signs and symptoms of monkeypox are characterized, after an incubation period of approximately 12 days, by fever, headache, muscle aches, backache, swollen lymph nodes, a general feeling of discomfort, and exhaustion.Within 1 to 3 days after the onset of fever, the patient develops a papular rash, often first on the face but sometimes initially on other parts of the body (Fig. 4).The lesions usually develop through several stages before crusting and falling off.The illness typically lasts for 2 to 4 weeks.No specific treatment is available, but smallpox vaccination has been used in people in contact with infected humans and people exposed to infected rodents.

Cowpox
Human cowpox is a relatively rare zoonosis which occurs sporadically in the United Kingdom and across Europe and in some western states of the former Soviet Union.The virus circulates in wild rodents, mainly field and bank voles and wood mice in the United Kingdom.Individuals having contact with infected cats or small rodents sporadically contract the disease from these animals.Several outbreaks occurred in western Europe (Germany, France) in people who had purchased infected pet rats from local suppliers.Pet rats are a novel potential source of local outbreaks.The morphologically distinctive skin lesions are mostly restricted to the patients' necks, reflecting the infected animals' contact pattern (Fig. 5).Individual lesions vaguely resemble orf or Milker's nodule but show marked surrounding erythema, firm induration, and local adenopathy.Older lesions develop eschar, leaving slow-healing, deep ulcerative defects after eschar separation.Severe flulike illness may be present in the acute phase.Smallpoxvaccinated patients tend to develop less severe reactions and heal more quickly.

Rabies
Because bites from pet rodents are frequent events, one must be concerned with rabies.No 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 to occur in woodchucks, squirrels, and even a rat.

Hemorrhagic Fever with Renal Syndrome, or Korean Hemorrhagic Fever, and Hantavirus Pulmonary Syndrome (HPS)
Hemorrhagic fever with renal syndrome is a group of rodent-borne viral diseases (hantaviruses) that are endemic or occur as focal epidemics on the Eurasian continent and in Japan.In general, hantavirus isolates from Asia or eastern Europe (Hantaan, Dobrava, and Seoul Diseases Transmitted by Less Common House Pets viruses) are considered more pathogenic to humans than the northern European strains (Puumala virus).Wild rodents in rural areas or wild rats in cities are the reservoirs of the virus, and they can shed the virus for several weeks.Several outbreaks involving laboratory personnel infected by laboratory rats have been reported in Japan and Europe.Hantaviruses cause chronic, apparently asymptomatic infections of their rodent hosts, but associated cases in humans may reveal the animal infection.The disease in laboratory personnel has been characterized by fever and a flu-like syndrome, with fever, myalgia, and a few days later, oliguria, proteinuria, and hematuria.Usually, patients recover without sequelae.The infection is contracted by handling infected animals or from contaminated aerosols.More recently, Seoul virus infection was identified in a patient who owned pet rats in Wales and also in pet rats in England.A pet rat imported in 2011 from the United Kingdom to Sweden was also detected to be infected by the Seoul virus in June 2013.Most laboratory rat suppliers employ 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 ELISA.
In the United States, HPS was first reported in the spring of 1993 and was caused by a virus called sin nombre virus.There were 465 reported human cases by the end of March 2007 (http://www.cdc.gov/ncidod/diseases/hanta/hps/noframes/caseinfo.htm), with a fatality rate of 35%.Most of the cases have been reported in the western states, especially New Mexico, Arizona, and Colorado.The reservoir of sin nombre virus is Peromyscus maniculatus, the deer mouse.Other hantaviruses have been identified in humans and various rodent species in North America, such as Black Creek Canal virus, which has been identified in Florida, with the cotton rat (Sigmodon hispidus) as the reservoir.Other viruses, such as Monongahela, New York, and bayou viruses, also cause HPS and are found in eastern Canada and the eastern and southeastern United States.In South and Central America, several hantaviruses have been identified as causing HPS, including Andes virus in Argentina and Chile; Andes-like viruses, including Oran, Lechiguanas, and Hu39694 viruses in Argentina; laguna negra virus in Bolivia and Paraguay; Bermejo virus in Argentina; Juquitiba virus in Brazil; and choclo virus in Panama.No cases in humans acquired by contact with pet rodents have been reported.

Encephalomyocarditis
Encephalomyocarditis is a rare disease in humans caused by an RNA virus of the family Picornaviridae.Sporadic cases have been reported, and the virus has been isolated from children in Germany and The Netherlands; in the United States, epizootics have occurred in pigs.Rodents, especially of the genus Rattus, have been considered the main reservoirs of the virus, and they transmit the virus to rats and other species through bites.However, no case from a rodent source has been identified in humans.

Hepatitis E
Hepatitis E virus (HEV) is an important cause of enterically transmitted human hepatitis in developing countries.While genotypes 1 and 2 of this virus infect only humans, genotypes 3 and 4 can spread from animals to humans and cause sporadic cases of human disease.However, autochthonous cases of hepatitis E have been reported in the United States and other industrialized countries.The source of HEV infection in these cases is unknown, but zoonotic transmission has been suggested.Pigs, and possibly also rats, may act as a reservoir for virus.Cases from consumption of raw deer or wild boar meat have been reported from Japan.Antibodies to HEV have been detected in many animals in areas where HEV is endemic and in domestic swine and rats in the United States.In this country, an antibody prevalence of almost 60% was reported for rats, with higher prevalence in rodents from urban habitats than in animals captured from rural areas.A 12% seroprevalence of HEV antibodies was reported for rats trapped in a valley in Nepal, where HEV was hyperendemic, and HEV RNA was detected in four animals.Phylogenetic analysis of the four genome sequences showed that they were identical and closely related to two human isolates from Nepal and distinct from the sequences of HEV isolated elsewhere.Similarly, in Japan, 114 of 362 (31.5%)Norway rats (R. norvegicus) and 12 of 90 (13.3%) black rats (Rattus rattus) were positive for anti-HEV IgG.Rats may play a role as a potential reservoir of HEV, but no cases of human infection from a pet rat have yet been reported.

Bacterial zoonoses Pasteurellosis
Among bite-transmitted zoonoses, infection by P. multocida is certainly the most common in domestic pets.Although most of the cases occur from cat and dog bites, rodents nevertheless harbor P. multocida in their oral cavities and can at times transmit the organism 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.A case of Pasteurella pneumotropica peritonitis was reported in a child maintained on peritoneal dialysis following contamination of the dialysis tube by a pet hamster.P. pneumotropica has been isolated primarily from rodents.The patient responded well to intraperitoneal tobramycin and vancomycin.Cultures of samples from infected bite wounds should always be performed to administer the appropriate antibiotics.Treatment should be carried out with amoxicillin-clavulanate potassium (Augmentin), 500 mg three times daily for 5 to 7 days, or doxycycline, 100 mg orally twice a day.

Rat Bite Fever
RBF is a rare disease that can be transmitted by rats, which are healthy carriers of Streptobacillus moniliformis or "Spirillum minus" in the nasopharynx.Streptobacil-lary RBF is a rare disease in the United States.Of 14 cases on record since 1958, 7 originated from the bites of laboratory rats.Bites by wild rodents (rats and squirrels) can also transmit the infectious agent.Infection has also followed consumption of contaminated raw milk.According to a case report from New Mexico, a 15-yearold boy was infected after he drank water from an open irrigation ditch next to a baseball field.In Europe, a case of septic arthritis of the hip due to S. moniliformis after a bite on the finger of a 14-year-old boy from a rat for sale in a pet shop was also reported.The case was successfully treated by arthrotomy, drainage, and joint lavage followed by administration of penicillin.In The Netherlands, a 43-year-old woman presented, after being bitten by a pet rat, with a generalized febrile illness; an exanthema with mixed maculopapular and pustular eruptions on the lower halves of the extremities, elbows, knees, palms, and soles; and severe arthralgia and asymmetric arthritis.In France, a case of septic arthritis following a pet rat bite was described in 2007.S. moniliformis was detected in the knee synovial fluid and identified by 16S rRNA sequencing.The patient was cured by an amoxicillin treatment.
A few fatal cases of RBF in pet shop employees have been reported in the United States.A 24-year-old male pet shop employee contracted the disease through a minor superficial finger wound on a contaminated rat cage.The disease progressed from a flu-like illness to a severe endocarditis and sepsis, leading to death less than 60 days after the initial injury.A 52-year-old woman who was a pet store employee and had been bitten by a pet rat developed a severe disease and died of S. bacilliformis septicemia.Similarly, a fatal case in a young boy who owned pet rats was reported in San Diego, California, in 2014.A survey for cases in that county between 2000 and 2012 found another 16 cases.Among the 17 cases, including that fatal case, the median patient age was 10 years (range, 4 to 67 years); 59% of patients were female, and 65% were healthy before infection.Most infections (94%) were petassociated; one patient had an occupational exposure (rat breeder).Sixteen of seventeen patients reported exposure to rats.Of these, 44% reported only having handled a rat, 38% reported being bitten, and 13% reported a scratch.These cases highlight a possible danger of keeping rats as pets.Streptobacillary RBF has an incubation period of 2 to 10 days, a rapidly healing point of inoculation, and abrupt onset of irregularly relapsing fever, asymmetric polyarthritis, shaking chills, vomiting, headache, arthralgia, myalgia, and regional lymphadenopathy.Two to four days after onset, a maculopapular Diseases Transmitted by Less Common House Pets rash appears on the extremities (Fig. 6).Endocarditis is a possible complication.Diagnosis of RBF is made by culture of the organism from the blood or joint fluid.Recommended therapy for RBF is penicillin G, amoxicillin, or tetracycline.Clindamycin can also be effective.
Spirillary RBF is an even less common disease, with an incubation period of 1 to 6 weeks.Clinically, "S.minus" infection differs from streptobacillary fever in the rarity of arthritic symptoms, a distinctive rash, and a common reactivation of the healed wound when symptoms appear.

Tularemia
Tularemia, also known as rabbit fever, is an acute febrile illness caused by Francisella tularensis.Rodents are very susceptible to the disease, which usually culminates in a fatal septicemia.Because the disease is transmitted mainly from rodent to rodent by ticks and fleas, having pet rabbits or rodents should not be a major risk for the transmission of tularemia.There have been documented cases of transmission from domestic cats and, more re-cently, from the bite of a squirrel kept as a household pet, which died minutes after biting a child.Cases among commercially distributed prairie dogs from Texas raised concerns about the human risk of contamination in the United States and abroad.A case of tularemia was reported in Colorado in April 2004 in a 3-year-old boy who had been bitten on the left fourth finger by a pet hamster just before it died.The boy had been exposed to six pet hamsters purchased in Denver.Each hamster had died of diarrhea within a week of purchase.The boy had a painful enlarged lymph node, fever, malaise, and skin sloughing at the bite site.

Plague
Plague is endemic in many wild rodents in the western United States.Although several cases in humans have been associated with pets, especially cats, there are no reports in the literature of transmission to humans from pet rodents.The potential commercial distribution of plague-infected prairie dogs in Texas in 1998 should remind people of the danger of keeping wild animals as pets.Recurrent outbreaks of plague in Peru were also associated with the indoor presence of infected guinea pigs, used as both pets and sources of food by the natives (P.Arambulo, personal communication).

Epidemic typhus
Epidemic typhus is caused by Rickettsia prowazekii and is usually transmitted from person to person by the human body louse.Sporadic cases have been reported in the United States for people living in rural areas after contacts with flying squirrels.Since 1976, approximately one-third of the 45 R. prowazekii infections documented in the United States occurred after contact with flying squirrels or their nests.

Leptospirosis
Although rodents, especially rats, are known to harbor and shed various Leptospira interrogans serovars for long periods, very few cases of human infection from pet rodents have been reported.In one instance, L. interrogans serovar Ballum was contracted from a pet mouse.More recently, leptospirosis was diagnosed in an HIV-infected patient in Germany who likely acquired his infection from his pet rats.The infection was due to L. interrogans serogroup Icterohaemorrhagiae or serovar Icterohaemorrhagiae or Copenhageni isolates originating from the patient's rats.A case of Weil disease was reported in the United Kingdom in 2008 from a pet rat owner and was traced back to a pet shop.Similarly, three cases between 2005 and 2010 were diagnosed in pet rat owners in the Czech Republic.Outbreaks in personnel working with laboratory rats and mice have been documented in Europe and the United States.

Salmonellosis
Guinea pigs are highly susceptible to salmonella infection and develop severe clinical disease (septicemia).In guinea pigs, high mortality is the rule.A family outbreak of salmonellosis due to contact with guinea pigs raised on a commercial ranch in Canada has been reported.More recently (2014), a case of Salmonella enterica serotype Enteritidis sternal osteomyelitis in a previously healthy child who cared for two recently deceased guinea pigs was reported and led to a multistate investigation.Ten cases among residents of eight states were identified, and four guinea pig outbreak strains were isolated.One patient was hospitalized; none died.The median patient age was 9.5 (range, 1 to 61) years.Among 10 patients, two purchased guinea pigs at independent stores, and three purchased them at different national retail chain (chain A) store locations; three were chain A employees and two reported guinea pig exposures of unknown characterization.Trace-backs identified four distributors and 92 sources supplying guinea pigs to chain A, including one breeder potentially supplying guinea pigs to all case-associated chain A stores.An outbreak of multidrug-resistant S. enterica serovar Typhimurium associated with hamsters purchased at retail pet stores in Minnesota occurred in 2004.Of 22 patients, 13 (59%) in 10 states reported exposure to pet hamsters, mice, or rats, and 2 (9%) had secondary infections.High mortality after showing signs of diarrhea was reported from several hamsters.The outbreak strain of S. enterica serotype Typhimurium was cultured from a patient's pet mouse and from seven hamsters from pet stores.Human, rodent, and environmental isolates were resistant to ampicillin, chloramphenicol, streptomycin, sulfisoxazole, and tetracycline.
Outbreaks have also been recently traced to rodents used as food for reptiles and amphibians.An outbreak of human Salmonella I 4,[5],12:i:-infections was associated with exposure to rodents sold as food for pet reptiles and amphibians (i.e., feeder rodents).This outbreak strain also was implicated in a 2009 outbreak in the United Kingdom and a 2010 outbreak in the United States, both linked to frozen feeder rodents from a single U.S. supplier, resulting in recalls.Therefore, pet rodents probably are an under-recognized source of human Salmonella infection.Mice and rats are also very susceptible and may carry subclinical infections for long periods.These infections are usually caused by S. enterica serovar Typhimurium or S. enterica serovar Enteritidis.If salmonellosis occurs in a child who has a pet rodent, the pet's feces should be cultured for Salmonella.However, shedding may be only intermittent.

Yersiniosis
Infections with Y. pseudotuberculosis and Yersinia enterocolitica may be contracted from pet rodents.Guinea pigs are commonly infected with Y. pseudotuberculosis.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 any symptoms.Children can be infected by fecal-oral contamination.In humans, the disease is observed mainly 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 by ELISA are also available.When the disease is mild (uncomplicated pseudo-appendicular syndrome), antimicrobial chemotherapy is not useful.Y. pseudotuberculosis is usually sensitive to ampicillin, aminoglycosides, or tetracycline.Y. enterocolitica is also found in rodents, which are usually healthy carriers.Chinchillas are very susceptible to the infection, and several epizootics have occurred in Europe and the United States.Guinea pigs also are commonly infected by Y. enterocolitica, but serotypes found in rodents usually do not affect humans.Y. enterocolitica affects mainly young children.The main symptom is an acute enteritis with watery diarrhea, sometimes bloody, lasting 3 to 14 days, and abdominal pain.Diagnosis is based on isolation of the agent from the feces of patients.Sero-diagnosis by ELISA on paired sera is also useful to determine infection.Aminoglycosides and trimethoprim-sulfamethoxazole are the most appropriate antibiotics.

Campylobacteriosis
Campylobacter spp.infection can occur in some rodent species.Proliferative ileitis, a specific enteric syndrome of hamsters, is probably caused by a strain of Campylobacter.Hamsters certainly represent a potential source of human infection, but no hamster-associated cases have been reported.In humans, Campylobacter infection is characterized by diarrhea, abdominal pain, Diseases Transmitted by Less Common House Pets cramps, fever, and vomiting.The diarrhea is frequently bloody.The incubation period is 2 to 5 days, and the disease usually does not last more than a week.Usually, treatment is limited to fluid replacement therapy.
Streptococcus equi subsp.zooepidemicus S. equi subsp.zooepidemicus is a facultative pathogen affecting animals and humans.Two severe human cases were linked epidemiologically and genetically to infected guinea pigs.S. zooepidemicus infections should be considered in patients who have severe clinical illness and report guinea pig exposure.

Parasitic zoonoses Cestodiasis or taeniasis (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 it may also be found in other rodents.
In a recent study of pet shops in central Anatolia, Turkey, 11% of the Syrian hamsters tested were infested with H. nana.Hymenolepiasis occurs primarily in children.The prepatent period is 15 to 30 days.Usually, the infestation 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.Humans may acquire the infection from infected rodents 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 in the intestine, liberating an oncosphere that enters a mucosal villus and develops into a cysticercoid larva within 5 days.The cysticercoid ruptures the villus, travels 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.Praziquantel (Biltricide) and niclosamide (Yomesan or Niclocide) are effective for treatment of Hymenolepis infection.Treatment of infected rodents can be done with 1 mg of niclosamide per 10 g of body weight given at 7-day intervals or with 0.3% active ingredient in the feed for 7 days.

Acariasis (Trixacarus caviae)
Several external parasites can infest rodents.Among these, T. caviae, a parasite found mainly 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.The skin is thickened, dry, and scaly.Flaky, thickened, pruritic skin lesions caused by T. caviae in a 3-year-old male pet guinea pig that presented for agitation and itching were recently reported in Germany.In 2009, an outbreak occurred in a colony of guinea pigs kept at a petting zoo in Japan.Treatment is based on a solution of 1:40 lime sulfur in water applied to the skin and repeated weekly for 6 weeks or a once-a-week application of 10% lindane for 3 weeks.Ivermectin injected subcutaneously at 200 mg/ kg is a useful treatment for ectoparasitism.Treatment of the infected guinea pig includes spot-on dermal treatment every 30 days on days 0, 30, and 60 with a topical 10% imidacloprid-1% moxidectin solution.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.For infected children, crotamiton (Eurax) in one application per day for 2 to 5 days is the most common treatment; lindane (1% g-benzene hexachloride) (Kwell) may also be used.

Fungal zoonoses Dermatophytosis
Tinea favus of rats and mice, caused by T. mentagrophytes var.quinckeanum, is widespread.Mice and guinea pigs are the important sources of human infection with T. mentagrophytes var.mentagrophytes or Microsporum gypseum.
In 2002 in a Slovakian family, dermatomycosis caused by T. mentagrophytes var.quinckeanum, the source of which was a pet guinea pig, was confirmed in the father and son.In a survey of skin diseases in pocket pets in southern Italy, dermatophytosis was the most common disease observed, especially in young animals.Rats, chinchillas, and hamsters are much less common sources of ringworm in humans.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 "Dermatophytosis" under "Rabbits" above).In rodents, oral griseofulvin at 15 to 25 mg/kg orally once daily for 3 to 5 weeks is the recommended treatment.

Sporotrichosis
A few human cases of lymphocutaneous sporotrichosis caused by Sporothrix schenckii have been associated with rodent bite accidents.

HEDGEHOGS
It is estimated that about 40,000 households in the United States own a pet hedgehog.Salmonellosis has been diagnosed in patients who own hedgehogs as pets.The African pygmy hedgehog (Atelerix albiventris) (Fig. 7) has been associated with cases of S. enterica serovar Tilene infection in children in the United States and Canada.Systemic mycobacteriosis caused by Mycobacterium marinum has been reported in pet European hedgehogs.The hedgehog had acquired the infection from the fish tank in which it was housed in a pet store.
Ringworm cases (inflammatory tinea corporis) caused by T. mentagrophytes var.erinacei have been reported from owners of pet African pygmy hedgehogs (Fig. 8).An outbreak among hedgehog owners was reported in Germany a few years ago.Eight hedgehog caretakers from Göttingen and the surrounding area developed dermatophytosis caused by Trichophyton erinacei.Four patients who handled the animals without gloves developed lesions on their hands that looked like hand eczema, whereas the caretakers who wore gloves presented with typical ringworm on their arms, big toes, back, abdomen, and thighs.Human cases are easily treated with oral itraconazole (200 mg daily for 7 days).The hedgehog can be treated by application of a miconazole-containing veterinary lotion.The African pygmy hedgehog has not yet been documented to carry any mycobacterial diseases; however, infection by various Mycobacterium species (M.marinum and Mycobacterium avium) has been reported for the European hedgehog.Therefore, hedgehogs are not recommended pets for patients with HIV infection.A case of infection in a pet hedgehog by Cryptosporidium has also been reported.Commercially available hedgehog pets may pose a risk for Cryptosporidium infection, especially for HIV-infected people.

REPTILES AND AMPHIBIANS
Reptiles are increasingly popular pets in the United States (Fig. 9): in 2009 4.7 million U.S. households owned 13.6 million pet reptiles (http://exoticpets.about.com/cs/resourcesgeneral/a/petstates.htm).During the period from 2001 to 2006, the number of turtles kept as pets in the United States increased 86% to nearly Diseases Transmitted by Less Common House Pets 2 million turtles.There is a large international trade of live reptiles, with the United States accounting for 80% of this trade.Over 10,000 green iguanas were imported annually in the United Kingdom during the 1990s, and the British Federation of Herpetologists estimates that there are 7 million to 8 million reptiles and amphibians being kept as pets in the United Kingdom (http:// exoticpets.about.com/b/2008/11/25/more-pet-reptiles-than-dogs-in-uk.htm).More than half a million reptiles were imported in Germany in 2007 through the Frankfurt am Main airport.Table 2 lists the major zoonoses transmitted by reptiles and amphibians.

Bacterial Zoonoses Salmonellosis
Salmonellosis is the most frequent and major zoonosis transmitted by reptiles, especially turtles, iguanas and lizards, and snakes (Fig. 10).Increasing evidence suggests that amphibians (e.g., frogs, toads, newts, and salamanders) also can pose risks for salmonellosis in humans.The CDC has emphasized the risk associated with ownership of reptiles and amphibians, because they are a well-established source of human salmonellosis.A study conducted in 1996 and 1997 attributed an estimated 6% of all human, laboratory-confirmed, sporadic Salmonella infections in the United States (and 11% of infections among people aged <21 years) to contact with reptiles and amphibians.Salmonella infections present the most significant hazard to children, who are at greater risk of disease than adults because they are frequently in close contact with animals and their handwashing practices are often not well developed.In a case-control study of sporadic Salmonella infection in infants, exposure to reptiles was among the main risk factors (OR, 5.2; 95% CI, 3.4 to 7.9), with cases exposed mainly to iguanas and lizards (25 cases each), snakes (20 cases), and turtles or tortoises (14 cases).For instance, in 1994, 413 (81%) of 513 S. enterica serovar Marina cases occurred in children aged 1 year.
Osteomyelitis can be a severe complication of Salmonella infection from pet reptiles.A 31-year-old immunocompromised patient developed sepsis and osteomyelitis due to Salmonella enterica subsp.arizonae secondary to exposure to iguanas and snakes kept as pets at her home.Beside that case, bone and joint infections due to this organism were reported in the literature in 23 patients (9 children and 15 adults).Eleven of the adults were female (73%), compared with three (33%) of the children (p < 0.01).Significant underlying illnesses were present in all 15 adults and in 5 children (55%, p <0.05); 10 (77%) of the adults were immunosuppressed, compared with one child only (17%) (p < 0.05).In 10 of the adults the knee was infected (67%), compared with 1 child only (11%, p < 0.01).Antibiotic therapy was prolonged in both adults and children, and in most cases consisted of 4 to 6 weeks of parenteral treatment.Complete cure and survival was attained in 11 of 15 adults (73%) and all 9 children.Optimal antibiotic treatment probably consists of ceftriaxone or a fluoroquinolone if the organism is susceptible.
In a study of children with invasive reptile-associated salmonellosis (RAS), the children were significantly younger than those with noninvasive disease (median age 0.17 and 2.0 years, p < 0.0001).RAS is most frequently seen after exposure to turtles (42%).However, children with invasive RAS had been exposed more often (p ≤ 0.001) to reptiles other than turtles, including iguanas, bearded dragons, snakes, chameleons, and geckos.Children exposed to those latter reptiles, usually kept indoors, were younger than children exposed to turtles, mostly kept outdoors (p < 0.0001).RAS in children is significantly associated with invasive disease at a young age, in particular, infants <6 months of age.
Pet turtles have been recognized as a major source of human salmonellosis since Hershey and Mason isolated S. enterica serovar Hartford from the pet turtle of a 7-month-old infant with serovar Hartford gastroenteritis.Subsequent investigations established that 14% of the estimated 2 million cases of human salmonellosis in the United States in 1970 and 1971 were linked to pet turtles, mainly the red-eared turtle (Pseudemys scripta elegans).
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 following enactment of the ban.Despite this prohibition, small turtles remain available to the public from various sources, including pet shops, flea markets, street vendors, and websites.From 2001 to 2006, the number of turtles kept as pets in the United States increased 86% to nearly 2 million turtles, suggesting that this exception might provide a mechanism by which small turtles become household pets.A multistate outbreak of Salmonella Paratyphi B var. Java infections related to pet turtles between 2007 and 2008 was reported in the United States.Furthermore, an estimated 3 to 4 million turtles are shipped annually from the United States and sold around the world.Consequently, several outbreaks of salmonellosis have been reported in Japan, the United Kingdom, Puerto Rico, Israel, and France.For instance, an outbreak caused by S. enterica serovar Tel-el-kebir was reported in Ireland among owners of terrapin turtles.In a study of salmonellosis in people from southwestern Germany, owners of puppies, kittens, or turtles were almost seven times more likely to have Salmonella infection than were healthy controls.
Turtles are usually healthy carriers of salmonellae, and shedding is very irregular, but they may shed salmonellae for up to 11 months.The problem of Salmonella Diseases Transmitted by Less Common House Pets infection in turtles arises from the widespread contamination and persistence of the microorganisms in turtle breeding ponds and nesting areas.Turtles can acquire the organisms in ovo or after hatching.The pattern of Salmonella excretion in amphibians and reptiles was studied in a vivarium over a 3-year period.Salmonella could be isolated about twice as often from animals kept under arid or mesic conditions as from animals living in humid or aquatic environments.Animals feeding on mice (P = 0.04) and reptiles in general (P = 0.04) more commonly excreted Salmonella.Use of antibiotics for attempted control of salmonellae in pet turtle husbandry has been widely practiced.In their attempt to eradicate salmonellae with gentamicin sulfate, turtle farmers have created an even greater health hazard through selection of antibiotic-resistant strains.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 containers.Identification of the microorganism from stool culture and an antibiogram should be performed any time 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 also be acquired from other reptiles, such as lizards or snakes, chameleons, and amphibians.The 1990s were characterized by an explosion in pet reptile ownership in the United States.Because the most popular reptile species (iguanas, for example) do not breed if closely confined, most reptiles are captured in the wild and imported.From 1989 through 1993, reptile imports to the United States increased by 82%, from 1.1 million to 2.1 million, with iguana imports increasing by 431%, from 143,000 to 760,000 animals.Pet iguana-associated salmonellosis cases in two infants residing in Indiana were reported in 1990, and many other cases have been reported from several states since then, underscoring the important role played by reptiles, particularly pet lizards, in the transmission of zoonoses.In several cases, a rare S. enterica serotype, Marina, was involved, and there was no direct contact between the pet iguana and the infant.These cases demonstrate that direct contact between the reptile and the infant is not necessary for transmission to occur.Similarly, a human case of salmonellosis acquired through a platelet transfusion from a donor with a boa constrictor was reported.
Isolation of rare serotypes of Salmonella spp.often alerts public health staff about possible transmission of infection from reptiles to humans.For instance, isolations of Salmonella serovars Marina and Poona from humans increased, respectively, from 2 and 199 in 1989 to 47 and 341 in 1998.Similarly, cases caused by a rare serotype, Poona, were associated with savanna monitor lizards (Varanus exanthematicus) imported as pets from Ghana and Togo.An outbreak of salmonellosis among children attending a Komodo dragon exhibit at a zoo was the cause of at least 65 cases of serovar Enteritidis infection.In 1995 there were as many as 6,700 reptilecaused salmonella infections in the United States, but the incidence may be closer to 80,000 cases per year, 80% of them in children.In Canada, an estimated 3 to 5% of all cases of salmonellosis in humans are associated with exposure to exotic pets.
A high proportion of reptiles (more than 90%) are asymptomatic carriers of Salmonella.Reptiles can become infected through trans-ovarian transmission or direct contact with other infected reptiles or contaminated reptile feces.High rates of fecal carriage of Salmonella organisms can be related to the eating of feces by hatchlings, a behavior typical of iguanas and other lizards.In a cohort study of 12 captive iguanas, fecal shedding of Salmonella organisms was monitored for 10 weeks.All 12 iguanas were found to shed Salmonella organisms at least once, and multiple serotypes were isolated from 7/12 animals.Salmonellae were isolated from 83% of the fecal samples tested.In a limited survey at a green-iguana farm in El Salvador to identify sources of Salmonella in green iguanas and their environment, Salmonella spp.were isolated from the intestines of both adult (3/20) and hatchling (8/20) iguanas and from the surfaces of 40% (7/ 16) of the eggs tested.Soil samples from a breeding pen and a nest in that farm were positive for Salmonella spp.
In the United Kingdom, more than a quarter of cases of salmonella in children aged under 5 are associated with exposure to pet reptiles.Findings also showed that children with salmonella linked to reptile exposure had more serious outcomes, including hospitalization and development of invasive disease.They were more than twice as likely to be admitted to hospital (48% versus 19%; P = 0.0002) and more than five times as likely to have invasive disease, including bacteremia, meningitis, and colitis requiring surgery, compared with cases not associated with reptiles (17% versus 3%; P = 0.0016).

Edwardsiella infection
Human infection with Edwardsiella tarda is uncommon.This organism can be found in cold-blooded animals, reptiles, and fish (goldfish, catfish, and bass).In humans, the organism may cause gastroenteritis resembling Salmonella infections.Wound infections, such as cellulitis or gas gangrene associated with trauma to mucosal surfaces, and systemic disease, such as septicemia, meningitis, cholecystitis, and osteomyelitis, have been reported.At least one case associated with a pet turtle was reported in the United States.This bacterium is susceptible to most commonly prescribed antibiotics, but fatal gastrointestinal and extraintestinal infections have been described.

Plesiomonas infection
Plesiomonas (Aeromonas) 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 in a zoo animal keeper infected by handling a sick boa constrictor has been reported.Diagnosis is made by stool culture.Treatment with trimethoprim-sulfamethoxazole (Bactrim or Septra) for 5 days is usually effective.

Yersinia infection
Y. enterocolitica has been found in water and on cold-blooded animals, such as frogs and fish.However, the serotypes involved are not usually found in humans.

Campylobacter fetus
During the course of an S. enterica serovar Agona case investigation, C. fetus was isolated for the first time from a pet turtle.This suggests that turtles, in addition to being reservoirs for Salmonella species, may also be reservoirs for C. fetus.

Serratia marcescens cellulitis
A case of cellulitis caused by S. marcescens was reported to have occurred in an 8-year-old boy who was bitten on his left index finger by a pet iguana.The Serratia isolate was resistant to ampicillin and Diseases Transmitted by Less Common House Pets cefazolin but was susceptible to ampicillin-sulbactam and gentamicin.

Melioidosis (Burkholederia pseudomallei) in iguanas
B. pseudomallei, the causative agent of melioidosis, was isolated from abscesses of two pet green iguanas in California.The international trade in iguanas may contribute to importation of this pathogen into countries where it is not endemic and put persons exposed to these animals at risk for infection.

Parasitic Zoonoses of Reptiles Pentastomiasis
Pentastomiasis, a zoonotic parasitic disease, has been reported commonly in Africa and Asia.It is caused by pentastomes, which are annulated but unsegmented bloodsucking endoparasites.Pentastomes (Armillifer spp.) are annulate metazoa that are almost exclusively parasites of the reptilian respiratory system.Pentastomiasis is endemic to western and central Africa.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.Most cases of human pentastomiasis are caused by two species of pentastomids, both of which have characteristics of arthropods and annelids, viz., Armillifer armillatus and Linguatula serrata.Humans can become accidental hosts by handling infected reptiles and touching contaminated hands to the mouth.In humans, the infection is usually asymptomatic.The encapsulated larvae may be found during laparotomies or can be diagnosed by radiographic examination.A few cases of infected patients presenting with abdominal discomfort, a patient presenting with an acute abdominal emergency, two isolated cases of lethal infection, and infection of the human eye have been reported.
Fewer than 20 cases have been reported during the past two decades in China, and cases in children have been especially rare.Three cases in pediatric patients were recently identified with severe systemic symptoms.The patients were two boys and one girl aged 3 to 13 years.They all had a history of snake or worm ingested from snake and initial symptoms of fever, abdominal pain, diarrhea, and weight loss.Eosinophilia, anemia, and elevated serum IgE levels were noted.Moreover, the large numbers of nodules, or even calcification, in the liver and/or lungs were noted by ultrasound, computed tomography or magnetic resonance imaging scans.

Mesocestoides (cestoda) infection
Infections with Mesocestoides spp., cestodes of mammals and birds, occur infrequently in humans.One case occurred in California in 1990 in a child who was exposed to a large variety of animals in a day care center.That case was unique in that the day care facility housed all the animals necessary for the complete life cycle of this cestode.Niclosamide was used to treat this child, with apparent success.

Cryptosporidium spp.
Tortoises, including pet tortoises, may disseminate Cryptosporidium oocysts in the environment.The identification of a zoonotic genotype in the feces of captive European tortoises indicates a potential risk for humans within the household.

Fungal Zoonoses of Reptiles and Amphibians
Very limited information is available on fungal diseases of reptiles and amphibians.It does not appear that reptiles and amphibians are a major source of fungal zoonoses.Dermatophytosis has been reported in different reptiles such as green iguanas, turtles, lizards, and snakes, for example, T. mentagrophytes var.interdigitale in green iguanas.Dermatophytosis caused by Trichophyton and Microsporum spp. in reptilian species has rarely been reported.Treatment of these infections in reptiles is based mainly on the use of itraconazole and ketoconazole (15 to 30 mg/kg orally once daily for at least 2 weeks) or amphotericin B and nystatin.

ORNAMENTAL (AQUARIUM) FISH
Over 1 billion ornamental fish comprising more than 4,000 freshwater and 1,400 marine species are traded internationally each year, with 8 million to 10 million imported into Australia alone.In Australia, it is estimated that 12 to 14% of the population keep ornamental fish as pets.In the United States, about 20 million household aquariums are maintained, accommodating an estimated 161 million pet fish, mostly from foreign countries (in Southeast Asia and South America) and Florida.There are about 24 million pet fish in the United Kingdom.However, very few cases of zoonosis are reported (Table 2), and no major outbreaks of human disease for which diseased fish were directly responsible have been reported recently.The main pathogens acquired topically from fish (through spine puncture or open wounds) are Aeromonas hydrophila, E. tarda, Erysipelothrix rhusiopathiae, M. marinum, Streptococcus iniae, Vibrio vulnificus, and Vibrio damsela.S. iniae has recently emerged as a public health hazard associated with aquaculture, and M. marinum often infects home aquarium hobbyists.With the expansion of aquaculture and the popularity of recreational fishing, medical practitioners can expect to see more infections of this nature.Among these bacterial diseases of fish, mycobacteriosis is a major concern.

Mycobacteriosis
Mycobacterial infections are among the major zoonoses that can be transmitted by aquarium fish.Mycobacterial infections are increasingly reported for fish fanciers who keep an aquarium.M. marinum, Mycobacterium fortuitum, and "Mycobacterium platypoecilus" have been associated with both fish and human disease for many years.Skin ulcers due to M. marinum, contracted from fish tanks, have been reported.In two cases, a cut on the hand had preceded the cleaning of a home fish aquarium.Infection by M. marinum, also known as swimming pool granuloma or fish tank granuloma, is characterized, after inoculation on abraded skin and an incubation period of 2 to 3 weeks, by papulo-nodules, ulcers, or verrucous plaques.These may progress into sporotrichoid lesions or into deeper infections involving tendons and bone.Invasive septic arthritid and osteomyelitis may occur in immunocompromised hosts.For instance, more than 650 cases occurred in the United States between 1993 and 1996, 49% of them associated with aquarium exposure and another 27% related to injury by aquarium fish.In France, 63 cases occurred between 1996 and 1998, 84% of which were associated with fish tank exposure.
In infected fish, granulomatous lesions are usually observed.M. marinum has an optimum growth temperature of 30°C.A diagnosis can be made by isolating and identifying the organism.Histopathological examination shows a nonspecific inflammatory infiltrate in the acute phase.In chronic lesions the histopathological pattern is a tubercle-like granuloma.Infected fish should be destroyed, and the aquarium should be disinfected (with 5% calcium hypochlorite solution) before other fish are added.In humans, infection resolves following treatment with minocycline (Minocin), 100 mg twice daily orally for 6 to 8 weeks.Use of rifampin (Rifadin or Rimactane) has also been very successful, although indications for therapy are controversial.

Melioidosis: exotic fish
Melioidosis is an uncommon disease in humans caused by Burkholderia (previously Pseudomonas) pseudomallei, with a wide range of clinical manifestations from unap-parent infection to a rapid fatal septicemia.The infectious agent is endemic in Southeast Asia, where it is saprophytic in certain soils and waters.Studies have shown that the water of tanks in which exotic aquarium fishes were imported was contaminated with this bacillus.Disinfection of aquariums with bleach between water changes should be recommended in pet stores to prevent the spread of infection.

Erysipelothrix infection
Erysipelothrix insidiosa infection has been reported to occur in humans contaminated by handling fish.It is an occupational disease affecting mainly fishermen and fishery workers.The organism can be found on the surface of the fish and produces skin lesions known as fish roses in humans.Erysipelothrix infection is almost invariably introduced through minor skin wounds.
Local erysipeloid most commonly occurs on the hands, with the occasional complication of local lymphangitis and lymphadenitis.Infection can lead to endocarditis.Of 49 recorded cases of E. insidiosa septicemia in the United States between 1912 and1988, 11 were associated with fish; 22% of infected humans contract the disease from fish or shellfish, and 38% are likely to die.Despite the potential of this organism to infect aquarium owners, no cases have been reported to occur in humans as a result of aquarium fish contamination.Penicillin is the appropriate treatment for erysipeloid, as are cephalosporins.

S. iniae infection
S. iniae is a pathogen of fish capable of causing invasive disease and outbreaks in aquaculture farms.It can also produce invasive infection, characterized mainly by cellulitis but also by sepsis, endocarditis, meningitis, and arthritis after skin injuries during handling of whole fresh fish.In 1995 and 1996, nine Asian patients in Toronto, Canada, had invasive S. iniae infections.Eight of the nine patients had bacteremic cellulitis.No cases associated with aquarium fish owners have been reported.More recently, two cases (one case of cellulitis and one case of osteomyelitis) were reported for two Chinese patients after they handled fresh fish for cooking.Most of the human cases have been reported in Asia and were related to fish preparation.Older age and underlying conditions were also identified as risk factors for developing invasive infection.

E. tarda and ornamental fish
Protracted diarrhea in a 2-month-old Belgian infant was associated with E. tarda, and the same organism Diseases Transmitted by Less Common House Pets was isolated from a tropical aquarium fish in the home of the patient.Similarly, fibrino-purulent arthritis in a young man who had his knee punctured by a silver cobbler (Arius midgleyi) was reported in Australia.He recovered after treatment, which included intravenous gentamicin.

Aeromonas and Comamonas bacteremia
A case of Comamonas bacteremia that could be related to tropical fish exposure has been described.The patient was treated successfully with levofloxacin.Comamonas species are environmental Gram-negative rods that rarely cause human infection.A. hydrophila infection in a wound can lead to cellulitis, muscle necrosis, or septicemia.It is commonly acquired by contact with mucus or tissues from infected freshwater fish, especially when hands have cuts or abrasions.

V. vulnificus and V. damsela
Vibriosis is an infection often acquired from saltwater fish.Wound infection by these bacteria may be mild or self-limiting or lead to severe cellulitis and myositis and fasciitis necroticans, sometimes mimicking gas gangrene.In Australia, V. vulnificus infection occurred in a 68-year-old man who was spiked in the buttock by the dorsal spine of a flathead.He had acute septicemia associated with cellulitis, skin necrosis, necrotizing fasciitis, and myositis, which resolved after administration of doxycycline.Similarly, a few cases of wound infections caused by V. damsela were reported in Australia, with one fatal case in a 61-year-old man who received a puncture wound from a catfish spine.

WILD CARNIVORES: FERRETS
Among the large variety of house pets, wild carnivores, especially ferrets, have experienced increasing popularity; an estimated 6,000 ferrets are sold annually.There are approximately 750,000 pet ferrets in about 335,000 households in the United States.Despite the fact that ferrets are enjoyable pets, much concern has been raised following severe injuries to children by ferrets kept as house pets.The state of California does not allow ferrets or several other exotic animals as house pets.As pets, ferrets can also represent a health hazard by transmitting several zoonoses to humans (Table 3).

Rabies
Like other carnivores, ferrets are susceptible to rabies.In the United States, fewer than 30 cases of rabies in domestic ferrets have been reported since 1958, most often from pet ferrets, some of which were acquired from pet shops.Rabies immunization of ferrets with an inactivated vaccine has been shown to be effective for at least a year.The U.S. Department of Agriculture granted approval on 8 February 1990 for the use of this vaccine in ferrets 3 months of age or older.Annual booster vaccinations are required.Since 1998, the National Association of State Public Health Veterinarians recommended in its compendium of animal rabies control that ferrets be treated like dogs and cats for postexposure management.Therefore, the previous requirements that all ferrets that have bitten human beings be killed and their brains be examined for rabies are no longer applicable.

Influenza
Ferrets are very susceptible to influenza viruses and have served for years as animal models in the laboratory.In ferrets, influenza 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.Cases of influenza in humans have occurred from contamination by aerosols from infected ferrets.Similarly, ferrets can be infected by humans shedding the virus.
A cluster of pandemic influenza A/H1N1 (pH1N1) infections occurred in 2010 in pet ferrets in Pennsylvania.The ferrets were associated with one pet shop.The influenza cluster occurred during a period when the existing human surveillance systems had identified little to no pH1N1 in humans in the Lehigh Valley, and there were no routine influenza surveillance systems for exotic pets.The index case was a 2.5-month-old neutered male ferret that was presented to a veterinary clinic with severe influenza-like illness.pH1N1 human infections were identified in the surrounding community, and five additional ferrets with influenza-like illness were linked to the pet shop.This simultaneous outbreak of ferret and human pH1N1 demonstrates the important link between animal health and public health and highlights the potential use of veterinary clinics for sentinel surveillance of diseases shared between animals and humans.shown to be experimentally susceptible to the SARS CoV, and it was also shown that they could efficiently transmit the virus to previously uninfected animals that were housed with them.It is noteworthy that only the ferrets developed clinical signs (lethargy, conjunctivitis) after infection and that some of them died of their infection.Therefore, owners of pet ferrets should be concerned about the risk of infection of their pets by a SARS or SARS-related virus and the possible transmission to humans.However, the natural reservoirs of CoVs related to SARS were shown to be Chinese horseshoe bats (Rhinolophus sinicus, Rhinolophus ferrumequinum, Rhinolophus macrotis, Rhinolophus pearsoni), civets being amplifiers of the virus.

Other Potential Zoonotic Pathogens
Ferrets can harbor several pathogenic microorganisms in their digestive tracts, especially Salmonella and Campylobacter.In a 9-month survey of ferrets used in biomedical research, 4% had Salmonella and 18% had Campylobacter jejuni or Campylobacter coli organisms isolated from their feces.Although no cases have been reported to occur in humans 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.Ferrets can harbor many other zoonoses, such as cryptosporidiosis (Cryptosporidium causes ill thrift and mucoid diarrhea), tuberculosis, and listeriosis.A case of zoonotic Giardia intestinalis was detected in a ferret exhibited at a pet shop.A pet ferret was diagnosed with M. avium infection after having weight loss, diarrhea, and vomiting.Ferrets share many parasites with dogs and cats (e.g., Toxocara and Ancylostoma spp.) as well as dermatophytes (Microsporum canis and T. mentagrophytes).
However, fungal diseases are uncommon in the domestic ferret.A few cases of disseminated coccidioidomycosis have been reported from ferrets from the southwestern United States, and all cases of dermatophytosis reported from ferrets occurred in animals that had been exposed to cats.Ferrets respond poorly to treatment compared with dogs and cats.

PET BATS
Among the uncommon exotic pet species, bats may represent a major public health issue, because bats can be infected with various lethal viruses, such as rabies, Hendra, and Nipah viruses.A case of rabies-associated virus infection was diagnosed in France in 1999 in a pet African bat (Rousettus sp.) imported from either Togo or Egypt and sold by a Belgian exotic-pet dealer to another pet dealer in Bordeaux, France, where the owner, who was from Nîmes, France, bought it.The virus was identified to be a Lagos bat lyssavirus (lyssavirus genotype 2).Cases of rabies have also been reported to occur in bats belonging to the same species kept in a zoological garden collection in Denmark.The incriminated virus was European bat lyssavirus 1a.Similarly, rabies is of major concern for people working in animal rehabilitation centers.The first human case of Australian bat lyssavirus was reported to occur in a 39-year-old female animal handler from Queensland, in November 1996, within 5 weeks after she was scratched and possibly bitten by a yellow-bellied, sheath-tailed bat (Saccolaimus flaviventris).The isolation of Kluyvera ascorbata from a fruit bat at a commercial aquarium in Seoul, Korea, was reported.It is the most infectious agent of the genus Kluyvera, which causes serious diseases to animals and humans.Fruit-bats are distributed in pet shops through the black market in Korea and, although unproven, become popular pet, increasing the risk of transmission of zoonotic diseases.

NONHUMAN PRIMATES
During the last 40 years, laws restricting importation of nonhuman primates into the United States have considerably reduced the number of primates appearing in the pet trade.However, nonhuman primates sometimes find their way into the hands of pet owners.Until the 1974 prohibition, New World primates, especially the squirrel monkey, were used extensively in the pet trade.
Because of close phylogenetic ties between humans and nonhuman primates, zoonoses transmitted by monkeys are numerous, some of them being particularly severe in humans.For public health reasons, as well as for animal welfare and environmental protection, I strongly support the policy that monkeys should not be kept as pets.
It is not my purpose here to present all the zoonoses that can be transmitted by primates, because excellent reviews have been published.A short table of the major and most severe zoonoses is included (Table 4).
Primates kept as pets are derived primarily from three sources: wild individuals, captive breeding, and surplus zoo stock.Between 2000 and2004, about 8,400 primates were imported into the United Kingdom.Of those, 99.3% were destined for biomedical research or commercial or captive breeding facilities-with just 0.69% for zoo-based captive-breeding and conservation programs.Only one primate was imported for personal reasons.In the United States, 20% of 383,800 primates used in research and testing during 1995-2001 were imported, but importation for private use has been illegal since 1975.However, according to Convention on International Trade in Endangered Species (CITES), 828 primates were imported to the United States for "personal use" between 1975 and 2006, of which 78% were macaques (Macaca spp.).Furthermore, this has done little to reduce the sale of primates as pets, because captive-bred offspring of animals purportedly imported before 1975 continue to be sold.Better regulatory systems in some countries make the importation of primates for the pet trade harder or unlikely, but illegal smuggling does occur.
Among the major zoonoses, salmonellosis and shigellosis are certainly the most frequent in monkeys, because gastrointestinal illnesses are very common.Nonhuman primates are also very susceptible to respiratory infections, and tuberculosis must be considered a major risk for monkeys and their owners or caretakers.Monkeys are very susceptible to Mycobacterium tuberculosis, Mycobacterium bovis, and M. avium, and suspect animals should not be treated, in view of the cost, length of treatment, and the risk of development of resistance, though exceptions are made for endangered species or apes in zoological collections.Monkeys are also very susceptible to some viral diseases, such as measles.Infected children can easily transmit the virus to pet monkeys.Some viral diseases of nonhuman primates may be deadly to humans who are infected.An example is herpes B virus, which may be shed by healthy Asian monkeys (mainly macaques) in their saliva.In a recent study of non-occupational-exposure incidents involving macaques in the United States, children were more than three times as likely to be bitten as adults.Herpes B virus must be assumed to be a potential health hazard from macaque bite wounds; this risk makes macaques unsuitable as pets.In monkeys, rabies is a rare disease, but cases have been reported to occur in pet monkeys vaccinated with live modified strains; thus, only inactivated rabies vaccines should be used to immunize monkeys.Simian foamy viruses (SFVs) are retroviruses that are prevalent in all species of nonhuman primates.Among 305 people who lived or worked around nonhuman primates in several southern Asian and Southeast Asian countries and who were tested for SFVs, 8 (2.6%) were confirmed to be SFV positive by Western blotting and, for some, by PCR.The interspecies interactions that likely resulted in virus transmission were diverse; five macaque taxa were implicated as potential sources of infection.Phylogenetic analysis showed that SFV from three infected people was similar to that from the nonhuman primate populations with which the infected people reported contact.Thus, SFV infections are likely to be prevalent among people who live or work near nonhuman primates in Asia.

TABLE 1
Zoonoses potentially transmitted by pet rabbits and rodents a Boldface indicates the most common zoonoses; brackets indicate rare zoonoses.

TABLE 2
Major zoonoses potentially transmitted by reptiles and aquarium fish a Boldface indicates the most common zoonoses; brackets indicate rare zoonoses.

TABLE 3
Major zoonoses transmitted by ferrets a Boldface indicates the most common zoonoses.An acute and often severe respiratory illness emerged in the southern part of the People's Republic of China in late 2002 and rapidly spread to different areas of Asia as well as several other countries around the world. a

TABLE 4
Major zoonoses transmitted by nonhuman primates a a Boldface indicates the most common zoonoses; brackets indicate rare zoonoses.