The experts recommend that a FIV positive cats should live with other positive cats or on their own. As there is a 2% chance of catching FIV from a postive feline house mate during normal living enviroment. 9http://www.catchat.org/fiv.html)

If the cat in question is aggressive and deeply bites a fellow house cat they have a very high chance of catching this illness (nearly 100%).

The only exception to the above is if an EXISTING housecat who does not fight with the other cats in the home is found to be positive, then it is acceptable to keep all cats inside and yearly test the currently clear animals.

Also an owner taking on a FIV cat will have to be sure that they have the money to cope with the higher vet bills, which are more likely to occur with a FIV cat versus a healthy clear cat.