Feline Immunodeficiency Virus (FIV) is a virus that makes your cat more susceptible to disease by suppressing its immune system. You CANNOT catch FIV from your cat, and FIV is NOT transmissible to humans (including children). FIV is strictly in felines. Your cat cannot give FIV to your dog, horse, ferret, etc. You cannot "spread" FIV with you throughout the day - humans cannot be carriers for FIV.
FIV is only transmissible through cat bites or blood transfusions with another cat. A FIV-positive cat can't infect other cats by sharing food bowls or sharing litter boxes or playing or sleeping together. FIV seems to be transmitted predominantly by bites, since the virus is shed in the saliva of the infected cat.
There is no cure for this virus, but if you keep your FIV-positive cat strictly indoors and in a healthy environment (i.e., away from any sick cats), he/she can still live a happy, long life. The most important point to stress is that FIV-positive cats MUST be kept away from other cats, however, multiple cats with FIV can live in the same household. Keeping your cat indoors - for their protection as well as the protection of other cats they would come in contact with - is one of the responsibilities of owning a FIV-positive cat.