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.
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.
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.
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
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.
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.
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.
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
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
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
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
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.
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)
Special thanks to Jill Nord, M. D. who researched and wrote the
section on Cat Scratch Disease.
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
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.
Copyright (c) 1991 Men's Health Crisis, Inc. All rights
reserved. Non-commercial reproduction is encouraged.
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