There is 2 forms of "having" FIV.
Being a carrier like jack. Where the virus is present in the blood stream, but they do not show any symptoms. They can however pass it onto other animals by biting as they are infectious.
Having full blown FIV, like AIDS which causes the immune system to shut down. Then they get all sorts of illness' and eventually their organs start to shut down.
Jack has a nice snuggly home made bed from fluffy, teddy material and is always fed on high quality cat food. When he starts to exhibit symptoms of full blown AIDS, we will get him put down
MadCat