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Feline immunodeficiency virus (FIV) was first
discovered in 1986 in a cattery in California where some cats appeared to have
an illness similar to AIDS (acquired immunodeficiency syndrome) in people.
Since that time, FIV has been discovered in every country that has tested cats
for its presence. It appears likely that FIV has been present in cats for a
great many years. The rate of infection varies from about 1% (in healthy cats)
to as high as 14% (in ill cats) in Canada and the U.S.A. FIV is often found in
cats who are positive for the feline leukemia virus.
FIV belongs to the same family of viruses as
HIV (human immunodeficiency virus) and immunodeficiency viruses in other
species. This family of viruses (Lentiviruses) are known for being
species-specific, for life-long infection, and for slowly progressive
diseases. FIV is not transmissible from cats to people, and HIV is not
transmissible to from people to cats.
FIV is known to be present in the blood,
saliva and cerebrospinal fluid of infected cats. However, the virus is
extremely fragile and does not survive outside the cat’s body. Therefore,
the main method of transmission of FIV from one cat to another is through a
bite wound during a cat fight. The virus is only rarely spread through casual
cat-to-cat contact. However, female cats infected with FIV during their
pregnancy can pass the virus to their unborn kittens.
Male cats are twice as likely as female cats
to be infected with FIV. This reflects the greater tendency of male cats
(especially those not neutered) to roam and fight with other cats. Outdoor,
free-roaming cats are more likely to contract FIV than indoor cats. The virus
is least common where cats are kept indoors or in rural areas where the cat
population density is low. In Japan, for example, where there are a large
number of free-roaming cats, the virus is three times more common than in the
U.S.A. The average age of infected cats is 3 to 5 years old.
When a cat becomes infected with FIV, there
may be no clinical signs for many years. However, we know that 4 to 6 weeks
after infection the white blood cell count declines and some cats will have
swollen lymph nodes. Also, some cats have a fever, anemia, or diarrhea at this
early stage. FIV is toxic to a type of white blood cell, the T helper cell,
that is critical to a healthy immune system. This virus slowly depresses the
function of the cat’s immune system, leading to chronic health problems and
opportunistic infections. Many FIV-positive cats have chronic inflammatory
conditions of the teeth and mouth. Other chronic problems, such as diarrhea,
pneumonia, skin disease, sinus infections and some eye diseases as well as
neurological problems have been seen in FIV-positive cats.
FIV is diagnosed by using a blood test which
detects antibodies against the virus in the bloodstream of the cat.
Veterinarians may test a cat for FIV if there are unexplained chronic symptoms
of disease in a major body system. As well, the American Association of Feline
Practitioners recommends testing cats being introduced into a household to
prevent exposing any existing cats to the virus. Kittens under 6 months of age
may carry antibodies to FIV acquired from their mother without having the
virus itself. Therefore, any kitten under this age who tests positive should
be retested when over 6 months old.
FIV-positive cats may live for many months or
years. With good health care aimed at recognizing and treating FIV-associated
problems early, these patients can enjoy good quality of life. All efforts
should be taken to preserve their health by protecting them against other
diseases and injury. This is best accomplished by requiring FIV-positive cats
to live indoors; this also helps to prevent spread of the disease. There
currently is no vaccine available against FIV, but research is actively being
conducted toward this goal.
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Health Index
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