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Gay Men's Health Crisis
Pet Care: Special Concerns for People with HlV Infection
Arthur Lubell
February 25, 1991
GMHC Treatment Issues 1991 Feb 25; 5(2): 3

There is no doubt that owning a pet can result in much enjoyment and emotional support. But many HIV-infected people have worried over the risks of contracting disease from their animals. Of course, there is no known evidence that HIV can be acquired or transmitted by cats, dogs or any other non-primates. But some zoonotic diseases (diseases transmitted from animals to people) are of special concern to people who are immunosuppressed. Simple and sensible precautions are advisable to minimize risk (28).

This article was written with common domesticated animals in mind. People with more exotic pets may have special concerns and should consult with a veterinarian. If you are adopting a new pet, avoid the following highrisk animals: stray or sick animals, especially animals with diarrhea; and exotic or wild animals such as monkeys. Some veterinarians feel that cats, rather than kittens, are safer pets for immunocompromised people. But the most -important advice is to have new pets examined by a veterinarian before bringing them home.

Pet Hygiene Keep your animal clean and well-groomed and make sure it is regularly vaccinated. Control fleas and ticks for your pet's health and your own. It is helpful to control roaches and flies because insects can sometimes carry zoonotic diseases. Also, minimize contact with your pet's saliva, urine, feces and vomit. Be especially careful to avoid your pet's licks, if you have sores on your face or hands. Clean up bodily fluids with disinfectant (use a solution of one ounce of bleach to a quart of water). When possible have someone who is not immunocompromised help with cleaning up after your pet. Remember to wash your hands after handling your pet, especially before eating or smoking.

It is helpful to keep your pets indoors. By doing so, you may be better able to protect them and yourself from contagious diseases carried by outdoor animals or found in infected soil.

Pet Food Feed your animal commercial pet foods only. Do not feed it raw or undercooked meat, eggs or unpasteurized milk. Also, do not let your pet drink from the toilet. If possible keep pets inside, or on a leash when outside, to stop them from eating infected rodents or birds, infected feces or soil, and garbage, where there may be raw meat. It is also important to control rodents indoors, as much as possible.

Birds Parrots and parakeets can acquire a rare but serious zoonotic disease called psittacosis. Transmission of this infection from birds to humans has been traced to contact with pigeons, ducks, turkeys, and chickens. The psittacosis organism is inhaled by humans and can cause high fever, chills and shaking, a dry cough and chest pains. Headache seems always to be the most prominent and severe symptom. Tetracyclines (drugs which are similar to penicillin) are effective in the treatment of psittacosis infection. On the whole, psittacosis is a fairly rare infection.

Cryptococcus is a fungal organism which has been found in old pigeon droppings. It is possible for people to become infected by breathing the fungus into their lungs. Cryptococcal infection is known to have a particularly rapid progression in people with AIDS and can infect the brain. Prevention is difficult, since most people with cryptococcal infection are unaware of exposure to pigeon droppings or other sites in nature where the fungus grows.

Cat-Specific Concerns Research so far has identified cats as the major source of pet- transmitted infections to the immunocompromised. This section focuses on diseases associated with cats and how their owners can minimize risk of infection.

Litter Box It is preferable to keep the litter box away from kitchen and eating areas. If at all possible, have someone else change the litter box daily. Use disposable plastic liners and change them with each new litter. Never dump used litter directly into the trash. Instead seal the plastic liner with a twist tie and place in a plastic garbage bag for disposal. Wearing a face mask will offer extra protection.

Disinfect the litter box regularly, as recommended by most veterinarians. Use boiling water and let stand for five minutes. This is the only disinfectant procedure which kills toxoplasma eggs. Always wash your hands after cleaning the litter box. Use plastic or rubber gloves for extra protection.

Toxoplasmosis Cats may be carriers of the protozoan Toxoplasma gondii, which is a parasite that invades healthy cells. Raw or undercooked meat may also contain the parasite in cysts, or pockets, containing thousands of organisms. When ingested the cysts are broken down by digestive fluids, and release invaders, called tachyzoites, which enter the bloodstream. These organisms have a special affinity for the heart and skeletal muscle and are known to infect the brain.

Toxoplasma gondii may also take on another form, called oocysts or fertilized eggs, which are produced during the sexual cycle of toxoplasma organisms. Members of the cat family can carry and excrete these parasite eggs at a rate of 10 to 20 million per day for 10 to 15 days after ingesting the organism. Cats first come in contact with the parasite through other outdoor animals, infected soil or prey, such as birds and rodents, or from their mother during pregnancy. The oocysts themselves become infectious 24 hours after excretion. They are spread to humans by contact with infected cat feces, or warm, moist soil where they can live for months. Additionally, direct contact with any material contaminated by the infected cat feces can result in human infection.

Controlling your cat's diet is the best way to prevent a pet from developing disease. It is worth noting that after a primary infection, most healthy cats will not shed oocysts again. Even if reinfection occurs, the volume of oocysts shed is so reduced that it may be insufficient to transmit disease. You may be able to determine if your cat has already been infected by consulting a veterinarian.

Another important prevention strategy is to cook all meats well-done -- especially lamb and pork.

Toxoplasmosis in HIV Historically, toxoplasmosis has been feared mainly for its damage to the human fetus. In the general adult population, it is a relatively harmless infection for people with normally functioning immune systems. Upon infection, most healthy adults come down with generalized flu-like symptoms: chills, fever, headache, muscle pain, and inflammation of the lymph nodes. It is estimated that between a third and a half of the American population have been exposed to toxoplasma. Most people have developed antibodies to toxoplasma which keep them safely asymptomatic.

Toxoplasmosis in people with HIV is usually a reactivation of a past infection. When the immune system of a person who has been previously exposed to toxoplasma becomes weakened by AIDS, a reactivation of toxoplasma may result in serious illness, especially encephalitis (inflammation of the brain). Toxoplasmic encephalitis, formerly considered a rare disease even in immunocompromised adults, is now the most commonly recognized opportunistic infection of the central nervous system in patients with AIDS. Approximately 30% of people with AIDS who have been previously infected with toxoplasma will develop toxoplasmic encephalitis (29). Detailed articles on toxoplasmosis appeared in Treatment Issues vol. 3, no. 1 and vol. 4, no. l.

Feline Leukemia Virus (FeLV) and Feline Immunodeficiency Virus (FIV) FeLV and FIV are different from their human counterparts, and neither is known to be transmittable to humans. Signs or symptoms for both diseases may be somewhat similar. The following are symptoms in cats to look out for: weight loss; decreased appetite; diarrhea or constipation; blood in feces; enlarged lymph nodes; difficulty with breathing; excessive drinking or urination; evidence of pain while eating; poor coat condition; skin rashes or sores; and infected or swollen gums which may result in tooth loss (30).

Diagnosis of FIV disease is based on the cat's history, clinical signs, and results from an FIV-antibody test. Blood tests may indicate FeLV, but a negative test result does not necessarily imply immunity to the virus. An FeLV-positive cat may live for months or years without signs or symptoms of the disease.

While there is no cure for either FIV or FeLV, some drugs and steroids for infected cats may temporarily control virus-related conditions, or allow for short periods of remission. There is a vaccine for FeLV, but it is recommended for healthy, FeLV- negative cats only. Recently, some controversy has arisen concerning the vaccine's efficacy, and newly developed FeLV vaccines should be available at vet clinics and offices in the future. FIV and FeLV weaken a cat's immune system, making it more susceptible to zoonotic diseases, which can be spread to humans. Treatments and supportive care can be complicated and expensive, as well as painful and prolonging for the pet. Some professionals recommend that people with immunosuppression give up cats that are infected with either FeLV or FIV, but the decision is personal and should be discussed with both a physician and a veterinarian.

Cat Scratch Disease It is estimated that there are 8,000 cases of catscratch disease (CSD) annually in the United States. Infection occurs primarily among children and adolescents, and now a growing number among people with AIDS. In people with normal immune function, a pimple develops at the site of a cat bite or scratch within three to ten days. Swelling at the bite or scratch, and sometimes swelling throughout the body may persist for months, accompanied by fever, fatigue, headache, weight loss, and other symptoms. Throughout these symptoms, the cat may remain healthy and have negative skin tests. Even in the most severe cases, CSD is a benign illness for healthy adults and the prognosis is uniformly good, with no fatalities reported.

In immunosuppressed patients, however, the illness may be more dangerous. In one case reported in the medical journal AIDS, a patient developed large painful lesions under the skin of his arms and legs, as well as red nodules on the larynx. After one week of treatment with 500 mg of erythromycin every six hours, the condition improved (31).

CSD is sometimes misdiagnosed as Kaposi's sarcoma because the lesions resemble each other. The following clinical features may help to differentiate between the KS lesions and CSD lesions: CSD lesions bleed more easily and have a red base; CSD lesions are usually tender or painful and are associated with an underlying bone lesion. Most importantly, CSD lesions respond to antibiotic therapy, including erythromycin, doxycycline and drugs used to treat tuberculosis, but do not respond to penicillin, cephradine, nafcillin or dicloxacillin (32).

While CSD seems to be a relatively rare complication of AIDS, it may be worth taking special skin tests for the bacteria causing CSD and to have a biopsy of suspicious skin lesions. If appropriate, antibiotic therapy can be initiated to resolve the lesions. To avoid scratches, HIV-positive people should keep their cats' nails trimmed short and may wish to discuss the pros and cons of declawing with a veterinarian. The disease, which is rare, seems to be more often transmitted by kittens than adult cats.

Conclusion Recent studies indicate that pets enhance the quality of life for the aging and ill. The psychological and physical benefits of pet ownership are especially important to people with AIDS. However, planning ahead is important, and there is nothing wrong with finding a new home for your pet should you decide you can no longer take care of it. For more information on pet care call Pets Are Wonderful Support (PAWS): (415) 824-4040 or Pet Owners with AIDS/ARC Resource Services, Inc. (POWARS) (212)744-0842.

Special thanks to Jill Nord, M. D. who researched and wrote the section on Cat Scratch Disease.

Footnotes: 26 ACTC trial # 120.

27 ACTG trial # 125, and AmFAR trial # SCH00oo1 28 These guidelines were adapted from Safe Pet Guidelines a publication of Pets are Wonderful Support (PAWS), P. O. Box 460489, San Francisco, CA 94146; (415) 826-8058.

29 McCabe et al. Toxoplasmosis The Time Has Come. NEJM 318:5;313-315.

30 Cornell Feline Health Center. The Feline Leukemia virvs and the Feline Immunodeficiency Virus. Cornell University, College of Veterinary Medicine. Ithaca, NY 14853-6401.

31 Van der Wouw PA et al. Disseminated cat-scratch disease in a patient with AIDS. AIDS 3:751,1989.

32 Koehler JE et al. Cutaneous vascular lesions and disseminated cat-scratch disease in patients with AIDS and AIDS-related complex. Ann Int Med 109 (6):449, 1988.

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