Melissa
Kaplan's
Herp Care Collection
Last updated
January 1, 2014
Potential Zoonotic Diseases in Exotic Pets
Amy B. Worell DVM. From Pulse, Journal of the Southern California Veterinary Medical Association, 1999.
Some of the common zoonotic conditions affecting exotic pets are difficult if not impossible to accurately identify and isolate in these animals.
Veterinarians in clinical practice that are seeing nontraditional pets as patients should consider and educate themselves regarding the potential zoonotic diseases that may be affecting their patients. Even though there are many potential zoonotic diseases that may occasionally affect these special animals, only the most common and frequently encountered conditions will be emphasized in this paper. Veterinarians treating exotic animals should be aware that physicians may be uninformed as to the zoonotic conditions affecting commonly kept exotics and that the animal owners themselves often are poorly informed as to zoonotic disease potentially housed in their pets.
Knowledge of zoonotic conditions affecting exotic animals is particularly important in immunocompromised individuals, such as those individuals undergoing chemotherapy or with immunosuppressive conditions.Some of the common zoonotic conditions affecting exotic pets are difficult if not impossible to accurately identify and isolate in these animals. Such would be the situation with Salmonella infections in reptiles and chlamydiosis in some avian species. These microorganism, in addition to difficulty in isolation and identifying the presence of the organism, may be intermittently shed from the animal, which further increases the challenge for identifying those animals which are subclinically affected.
Avian
Species
Chlamydiosis/Ornithosis (caused by the organism Chlamydia
psittaci) is one of the best known and most common of the zoonotic
diseases affecting companion birds. The presence of this bacterium in
birds is often difficult to identify in the living patient, as the organism
is only intermittently shed. Definitive diagnosis in the live bird involves
isolation of the organism. Presumptive diagnosis in the live patient can
be highly suggested by clinical signs, species affected, and a variety
of supporting laboratory tests. Birds can be subclinically affected or
may demonstrate various signs of the disease. Clinical signs in affected
birds may include decreased egg production and hatch-ability to the more
common gastrointestinal or respiratory conditions. Clinical signs in affected
people can be described as similar to a common flu that does not resolve
in a short period of time. High temperatures and back pain may be noted.
Newcastle disease is a serious and fatal viral disease of avian species. Affected birds may demonstrate neurological signs that progress to death. Definitive diagnosis is through viral isolation of the organism. The disease is quite contagious among birds, and has zoonotic potential that often may go unrecognized. Clinical signs in people most commonly involve a mild conjunctivitis, which is self-limiting. Mycobacterium avian (and possibly other species) is the causative agent of tuberculosis. Affected birds may carry the disease for years, with intermittent organism shed. Clinical signs in avian species generally involve a significant weight loss in a poor-doing bird. Definitive diagnosis is accomplished through viral isolation and identification of the organism, although the acid-fast test on tissue samples is commonly used for a diagnosis of avian TB. Avian TB is considered a potential zoonotic disease especially in immunocompromised individuals. Clinical signs in people would be associated with respiratory signs.
Other potential zoonotic diseases affecting avian species include Giardia, Salmonellosis, Campylobacteiosis, Yersiniosis, and allergic alveolitis. In this last condition, which is also called hypersensitivity pneumonitis, people become hypersensitized to avian antigenic substances such as feathers and fecal material. It most commonly occurs with exposure to pigeons and budgerigars.
Reptiles
Salmonella presence in many species of reptiles has
been frequently documented in the literature and in lay publications.
Estimations, for example, of the commonly kept green iguana (Iguana
iguana), suggest that up to 90% of these animals may harbor this organism.
As with other zoonotic infections affecting exotic animals, this bacterium may be carried for years, and intermittently shed from the animal. Isolation of the organism from reptiles is difficult at best, and lack of isolation of the organism does not preclude its presence in an individual. Estimations, for example, of the commonly kept green iguana (Iguana iguana), suggest that up to 90% of these animals may harbor this organism. Clinical signs in carrier animals are probably nonexistent, while clinical signs in affected people can include severe diarrhea, abdominal pain, and death. Actual documented cases of reptile originated human Salmonella infections are not common, especially considering the large numbers of these animals that are kept as pets. As with many potentially zoonotic infections, children and immunosuppressed individuals are at greater risk for infection. Culturing reptiles for the organism is not routinely done as the organism is intermittently shed from the intestinal tract. If one elects to culture for the organism, then the literature suggests that five negative cultures would suggest a reptile free of Salmonella. A new Salmonella PCR is also available which is genus-specific for Salmonella. It has been suggested that three negative PCR tests can be considered as five negative culture tests.
Other potential zoonotic diseases include Campylobacter and several Mycobacterium species.
Rabbits
Cheyletiella
infections are intermittently noted in rabbits. Appearing as “walking
dandruff” on the dorsal thoracic and lumbar areas of the body, the
infections often go unnoticed by rabbit owners. Diagnosis is through direct
microscopic visualization of the organism. Clinical signs other than the
presence of dermatitis consisting of white flakes of skin are uncommon.
Affected rabbits generally are not pruritic and demonstrate little or
no alopecia. Zoonotic infections are considered possible, although extremely
uncommon.
Dermatomycosis infections in rabbits should be considered in the differential diagnosis of an alopecic or pruritic rabbit. Both Microsporum and Trichophyton species can occur. Diagnosis is through culture of the organism, and clinical signs are similar to other mammals. Infections in people generally involve classical pruritic ringworm skin lesions. Zoonotic potential seems to center on an individual’s susceptibility to the infection rather than mere exposure to the fungus.
Hedgehogs
Sarcoptic
mange is a common skin condition of hedgehogs. As with other species,
the affected animal can be extremely pruritic and demonstrate excessive
skin flaking. Diagnosis is through identification of the mite, which can
sometimes be accomplished through microscopic examination of the flaky
skin that falls off the pet. This method often is easier than obtaining
a skin scraping on an awake hedgehog.
Dermatophytosis is sometimes identified in hedgehogs. The most common causative agent is Trichophyton, with a variety of species. Clinically affected hedgehogs may have scaling along the ear margins and face, mild pruritis, and quill loss. Trichophyton of course, has zoonotic potential.
Ferrets
Human influenza
virus which can be readily transmitted from people to ferrets can occasionally
be transmitted back to people from ferrets. Vaccination of ferrets though,
is not recommended, as vaccination only produces short-term immunity and
the disease itself is relatively self-limiting. Rabies virus is a rarely
reported condition in ferrets. Ferrets though are susceptible to the virus,
and annual vaccination with an approved killed vaccine (Imrab 3, Merial,
St. Louis, Missouri) is recommended. Microsporum, Trichophyton,
Salmonellosis are also potentially zoonotic conditions affecting ferrets.
Guinea
Pigs
Scabies is
intermittently encountered in pet guinea pigs. Affected pigs are often
covered with a flaky white material that mainly affects the dorsum of
the pig. They are often extremely pruritic and may seizure during examination
or with stress. The mite can transiently affect people. Dermatophytosis
caused by Trichophyton species is sometimes seen in guinea pigs.
As with other animals susceptible to ringworm, zoonotic potential exists.
Pocket
Pets such as Mice, Rats, Hamsters, and Gerbils
Salmonellosis and dermatomycosis are occasionally encountered
zoonotic infections in small pocket pets. Pot Bellied Pigs Sarcoptic mange
can be fairly commonly encountered dermatological condition in pet pot
bellied pigs. As with other scabies mites, the condition is potentially
zoonotic.
Suggested References
1. Ferrets, Rabbits, and Rodents. Clinical Medicine and Surgery. E. Hillyer, K. Quesenberry, W. B. Saunders, Philadelphia, 1997.
2. Handbook of Rodent and Rabbit Medicine. K. Laber-Laird, M. Swindle, and P. Flecknell. Elsevier Science Ltd., New York., 1996.
3. Avian Medicine and Surgery. B. Altman, S. Clubb, G. Dorrestein, K. Quesenberry. W. B. Saunders, 1997.
