Infectious and fatal, these three diseases are known by a confusing set of initials - FeLV, FIV and FPV. Once your cat becomes ill with any of these diseases he or she will eventually die. There are no effective treatments or cures. What will save cats' lives is preventing the spread of these infections through blood testing and vaccination. All three of these infections can be carried and spread for long periods of time by cats who are harboring the viruses with no obvious symptoms of disease.