Overview of FIV
Feline immunodeficiency virus (FIV) causes an infectious disease in domestic cats and cheetahs similar to human immunodeficiency virus (HIV infection) in humans. It attacks and weakens the body's immune system, making the animal susceptible to infections and diseases that don't usually affect healthy cats. There is no cure for FIV, and the use of vaccines to prevent infection is somewhat controversial.
FIV is a lentivirus, a virus that causes slowly developing disease. Though eventually fatal, an FIV-positive cat can live for many years without any signs of illness.
FIV occurs worldwide and its prevalence varies geographically. About 1.5 to 3 percent of cats in the United States are infected with FIV. About 5 percent of FIV-positive cats also have feline leukemia virus (FeLV).