The most common route of infection is via bites from other cats or parenteral transmission. Therefore the virus is more prevalent in male cats, which tend to be involved in more catfights. FIV has been isolated in the salivary gland epithelium. The virus has also been isolated in utero and post parturient milk of lactating queens. Therefore there is a risk that kittens may become infected in utero or from drinking contaminated milk the risk is relavitely low (4). There is also a chance that kittens born from an infected queen may develop anti-FIV antibodies and therefore may not be infected (3). A low incidence of transmission may also occur via sexual intercourse where are a male cat may transmit the virus through the semen.(6)
Once cats are infected they remain infected for the remainder of their life (10).