Feline immunodeficiency virus is similar in structure to the human immunodeficiency virus, but these two viruses are not infective between cats and humans.
FIV is transmitted primarily through bite wounds inflicted during cat fights. Transmission between a mother cat and her kittens has been known to occur. Transmission of FIV among strictly indoor cats within a stable household is unusual as these cats do not usually bite one another hard enough to break the skin. Therefore, an FIV-positive cat in a household does not pose as great a threat as an FeLV-positive cat in the same household. Even so, bringing an FIV-positive cat into a household is not advisable.
In the earlier stages of the disease, cats may experience vague symptoms such as recurrent fevers, anemia and weight loss. As the disease progresses, chronic secondary infections develop, including upper respiratory tract infections, bacterial infections of the bladder and kidneys, and severe, progressive infections of the gums. Weight loss and lymphadenopathy, or enlargement of the lymph nodes, are common.
Opportunistic infections that would not normally make a healthy cat sick become problematic in cats with FIV. Some cats develop neurological signs, such as twitching of the face and tongue, loss of litter box training and compulsive roaming.
An FIV vaccine is not yet available. The only way to prevent the disease is to avoid exposure to other cats that may be carrying the virus, which usually means keeping your cat indoors.
Cats may test negative for some time after they are exposed and should be retested 90 days after possible exposure. Maternal antibodies-passed to kittens from the mother in the colostrum-interfere with the accuracy of the FIV test in kittens younger than 6 months. Testing of kittens is recommended after they are 6 months old.