I was looking at an Isacc Asimov web page and came across the news that he had AIDS. He contracted it when he had his heart surgery back in 1983. His doctors asked them not to reveal this to the public. Only after his death was this revealed.
http://www.locusmag.com/2002/Issue04/Letter.html
http://www.locusmag.com/2002/Issue04/Letter.html