Feline immunodeficiency virus (FIV) was first recognized in 1986 in a cattery in California. FIV is different from other feline retroviruses (Feline Leukemia). The virus is a member of the lentivirus family and has relatives that cause human immunodeficiency (HIV), equine infectious anemia, bovine immunodeficiency, medi-visna virus illness in sheep, and caprine arthritis/encephalitis in goats. In addition, over 25 large cat species including, cheetahs, lions, and panthers have their own strain of the virus. Despite similarity among these viruses, transmission among species has never been documented. Scientists think that FIV is an old virus and may be the grandfather of all immunodeficiency viruses. Comparison of its' genetic code point to a virus that is millions of years old. Years ago Lions of the Serengeti area in Africa almost went into extinction because of FIV infection. At some point, the lions went through an "adaptive episode" and have attained a peaceful arrangement with FIV.
A diagnosis of FIV positive means that antibodies to the virus were detected in your cat's blood. The immune system reacts to the presence of the virus by making proteins (antibodies) to fight the infection. They will remain in the body for the life of the infected individual. FIV infected cats initially have flu-like symptoms - fever lasting several days, lack of appetite, a decrease in white blood cells, and swollen lymph nodes. They may have diarrhea, anemia, and just act off. This can last four to six weeks. Once the full immune response is over, the virus is cleared from the blood stream and moves to the lymph nodes. Cats become asymptomatic and seem normal for months to even years. However, chronic diseases and opportunistic infections often mark the cats life. Gingivitis, stomatitis (bad breath), periodontitis, chronic diarrhea or constipation, pneumonia, lower urinary tract disease, neurologic disease, and skin diseases have been reported in FIV positive cats. Basically, the virus hides in the body eating away at the immune system. FIV infected cats usually die with severe wasting as a result of another opportunistic infection. FIV is shed in the saliva and transmission is from cat bite wounds. FIV-negative female cats bred by infected tom cats have remained negative as have their kittens. This suggests that venereal and in utero transmission of FIV is rare to nonexistent. Unlike feline leukemia virus, FIV is rarely found in the mother's milk. These facts explain why there is little worry of transmission through mutual grooming and intimate, non-biting type contact among house mates.
The best method to prevent disease is to identify FIV infected cats and prevent exposure to other cats. Prevalence of FIV is more significant in stray tom cats. FIV infection has been identified in 5 to 10% of the sick cats brought to veterinary hospitals in the United States and in as many as 30% in other countries. There is no vaccine currently available against FIV. Pets kept indoors away from free roaming cats are unlikely to acquire new infection.
We recommend that all kittens and cats over six months of age be tested for feline aids. No test is 100% accurate all the time. Any critical decisions about the care or life of a cat should be based on more than one test result. FIV infection carries a better prognosis than does Feline Leukemia infection. We have seen FIV positive healthy cats that live many months to even years after diagnosis. A good quality of life and preventing spread of FIV to other cats can be accomplished if pet owners work closely with their veterinarian to recognize and treat FIV-associated disease early in its' course.
Mark W. Richards, MS, PhD, DVM