Feline Leukaemia Virus (FeLV)
Feline Leukaemia virus (FeLV) is probably the most important virus in cats. About one in three cats that come into contact with the virus develop a permanent infection which is almost always fatal. FeLV infection causes a wide range of symptoms and by weakening their immune defences it can also make cats more susceptible to other infections. The effects of the virus on the immune system are similar to those that occur in humans with AIDS, but FeLV only affects cats. It cannot affect humans or other animals, such as dogs.