Care and Use of Animals

Zoonotic Diseases


Zoonotic Diseases: Sheep, Goats, and Cattle

Leptospirosis: Leptospirosis is widely distributed in domestic and wild animals. The possibility of transmission to humans from most animal species maintained in the laboratory should be considered but livestock and dogs would be the most common reservoirs. Transmission of the organism to humans can occur through skin abrasions and mucous membranes by contact with urine or tissues of animals infected with Leptospirosis. Inhalation or ingestion of organisms can also transmit the diseases. Disease can vary from asymptomatic infection to severe disease ranging from flu-like symptoms to liver and kidney failure, encephalitis, and pulmonary involvement.

Prevention: Control of this infection in laboratory animal populations along with use of protective clothing and gloves by persons working with and caring for infected animals will help prevent disease.

Cryptosporidia: Cryptosporidium species have a world wide distribution and can be found in many animal species including guinea pigs. Cryptosporidiosis is caused by a protozoan parasite which lives in the intestine of mammals. Cryptosporidiosis is transmitted by the fecal-oral route and can cause diarrhea in humans. Usually the diarrhea is self-limiting but in immunocompromised individuals the disease can have a prolonged course.

Prevention: Appropriate personal-hygiene practices which include washing hands after contact with animals or their waste should prevent spread of this organism

Q Fever: Q fever is caused by, Coxiella burnetii which is a rickettsial organism. Infection is widespread in domestic animals and includes sheep, goats and cattle. Humans can be infected by inhalation of infectious particles. The organism is shed in urine, feces, milk, and birth products of domestic sheep, goats, and cattle. Symptoms in humans are usually flu-like. In some cases more serious symptoms can occur especially in elderly patients or in immuno-suppressed people. During pregnancy, Q fever infection has been associated with prematurity, low birth weights and placentitis with miscarriage possible. Thus, pregnant animal handlers should not expose themselves to animals or their birth products which could potentially carry the Q-fever organism.

Prevention: Serologic status of individual sheep is not an accurate indicator of whether an animal is shedding organisms but consistently negative serology on a herd basis does provide some assurance of Q fever - free status.

Psisttacosis (Ornithosis, Chlamydiosis): Psittacosis is caused by the bacteria Chlamydia psittaci. C. psittaci is common in wild birds but can also cause enzootic abortion in sheep, goats, and cattle. Exposure to birth fluids and membranes of infected sheep and goats has been reported to cause gestational psittacosis in pregnant women. Symptoms of this zoonotic disease can include pneumonia, sepsis, and placental insufficiency resulting in premature birth or miscarriage.

Prevention: Pregnant animal workers should avoid contact with parturient sheep and goats.

Contagious Echthyma (Orf): Orf is caused by a pox virus and is endemic in sheep and goat herds in the United States. Orf produces pustular lesions on the lips, nostrils, mucous membranes of the oral cavity in infected animals. Humans are infected by direct contact with exudates from the lesions or from fomites. The disease in humans is characterized by similar lesions on the hand, arm, or face or the person infected.

Prevention: Personnel who handle sheep, goats and cattle should wear protective clothing and gloves and practice good personal hygiene.

Rabies: The incidence of rabies in wildlife in the United States has increased in recent years and there is a possibility of transmission to dogs and cats with uncertain vaccination history. Rabies is very rare in the laboratory environment but any random source animal or wild animal showing central nervous system signs must be considered a potentially rabid animal. The rabies virus is most commonly transmitted to other animals or humans by the bite of a rabid animal or by introduction of saliva containing the virus into skin wounds or intact mucous membranes. Rabies produces a fatal acute viral encephalomyelitis.

Prevention: Pre-exposure immunization should be available to personnel working with or caring for animals of uncertain vaccination status or those who work with wildlife known to be reservoirs of rabies.

Escherichia coli 0157:H7: The bacterial organism E. coli strain 0157:H7 can be found in the intestines of healthy cows. Meat can become contaminated during slaughter and milk can be contaminated from bacteria on the cow's udder or on milking equipment. Other sources of infection include eating sprouts, lettuce, salami, unpasteurized milk and juice and swimming in or drinking sewage-contaminated water. Infected persons often have bloody diarrhea and abdominal cramps. In children under 5 years of age and the elderly, an E. coli 0157:H7 infection may cause hemolytic uremia and resulting kidney failure. Persons with diarrhea can transmit this organism to other people if personal hygiene is inadequate.

Prevention: Good personal hygiene to include frequent handwashing and observing no eating or smoking rules in animal areas will help to prevent this zoonotic disease.

Salmonellosis: Along with a variety of other species, Salmonella, and other enteric bacteria are capable of causing disease in humans. Salmonellae are transmitted by the fecal-oral route. Infection produces an acute enterocolitis and fever with possible secondary complications such as septicemia.

Prevention: Use of protective clothing, personal hygiene which include hand washing after contact with animals or their waste, and sanitation measures prevent the transmission of the disease.

Ringworm: Dermatophytes, which are fungi, cause ringworm in humans and animals. Infection in animals may be inapparent and is transmitted to humans by direct contact with infected animals or by indirect contact with contaminated equipment or materials. Dermatophytes produce flat, circular lesions that are clear in the center and crusted and red on the periphery.

Prevention: The use of protective clothing, disposable gloves, and hand washing along with good personal hygiene will help to reduce the spread of dermatophytosis in a laboratory animal facility.

References:

Risk assessment- UC Davis
http://ehs.ucdavis.edu/animal/risk/index.cfm

Occupational Health and Safety in the Care and Use of Research Animals, National Research Council; National Academy Press, 1997.

Center for Disease Control- Division of Bacterial and Mycotic Diseases
http://www.cdc.gov/ncidod/dbmd/

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