"FIV stands for Feline Immunodeficiency Virus. It's a lentivirus, meaning that it progresses very slowly, gradually affecting a cat's immune system. It is passed through blood transfusions and through serious, penetrating bite wounds - mainly by stray, intact tom cats. The most well-known lentivirus in humans is HIV. But the two are not at all the same, and you can't get FIV from a cat. In fact, the only thing about FIV that you can catch is a bad case of the rumors.
As long as cats with FIV are not exposed to diseases that their immune system can't handle, they can live perfectly normal lives. "