infectious diseases in humans can be acquired through contact with pets.
Dogs and cats may be the most frequent household pets around the world,
but there are also many other vertebrates that share our household environment.
At least 55% of all households in the United States have a dog or a cat,
and 15 to 20% have pet birds, but the pet population is also composed
of millions of rodents, reptiles or aquarium fish, not to mention less common
species such as wild carnivores, monkeys or more recently the miniature
pig. It is estimated that 20 million American homes have aquariums.
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.
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.
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. Among the infectious
diseases Pasteurella multocida may cause cutaneous infection in
humans. 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. More
commonly some external parasites of the rabbit including fur mite acariasis
(Cheyletiella) and dermatophytosis (Trichophyton) may be
transmitted to humans.
(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. 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
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. 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.
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, 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
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. 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.
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. 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 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. 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. 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.
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.
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.
Tinea favus of rats and mice, caused by Trichophyton quinckeanum,
is widespread. 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).
rat bite fever, tularemia and rabies).
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,
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.
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. Arkless described infection caused by the bite of a pet
mouse. Infection has also followed consumption of contaminated raw milk.
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.
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.
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
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. 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.
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.
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. Y. pseudotuberculosis
is usually susceptible to aminoglycosides, trimethoprim-sulfa-methoxazole
is also found in rodents, which are usually healthy carriers. Chinchillas
are very susceptible to the infection and several epizootics occurred
in Europe and the United States. 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.
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. 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
Plague is an endemic
disease in many wild rodents in the Western United States. Several human
cases have been associated with pets, especially cats, but there are
no literature reports of transmission to humans from pet rodents.
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.
Outbreaks in personnels working with laboratory rats and mice have keen
documented in Europe and in the United States.
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 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 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.
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.
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
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
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.
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. 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).
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, Great Britain,[38, 39] Puerto Rico,
Israel, and France. Turtles are usually healthy carriers of Salmonella
and shedding is very irregular, but they may shed Salmonella for up to
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. 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. 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.
can be acquired not only from pet turtles but also from other reptiles
such as lizards or snakes, from frogs or aquarium fish.
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.
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.
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.
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 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. Among the bacterial diseases, mycobacteriosis
is certainly of major concern.
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. 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. 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. However, minocycline
should not be used for children less than 9 years old. Use of rifampin
(Rifadin®, Rimactane®) has also been very successful, usually
in association with ethambutol and trimethoprim-sulfamethoxazole.
Melioidosis and exotic
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 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.
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
Among the large variety of house pets wild carnivores, especially ferrets,
have experienced increasing popularity, with an estimated 6000 ferrets
sold annually (Table
3). According to the report of Ruprecht et al., 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. As
pets ferrets can also represent a health hazard by transmitting several
disease agents to humans.
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. Rabies immunization of ferrets
with an inactivated vaccine has been shown to be effective for at least
a year. 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.
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. Similarly ferrets can be infected by humans
shedding the virus.
Other potential zoonotic
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. 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. 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
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
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.
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.