FIV is a virus that is related to HIV, the human AIDS virus. Experts do not believe FIV is capable of infecting humans. FIV causes a syndrome in cats that is similar to human AIDS.
Most FIV-infected cats catch the virus by fighting with other cats. The virus spreads when an infected cat bites a cat that is not infected. A much smaller number of cats catch the virus from their mother as kittens. Sexual transmission of FIV does not appear to be common.