AIDS....
I think the odds of Arafat having AIDS, even if he were a rampant homosexual, are quite slight. I'm not sure why there's such a fascination with this remote possibility.
However, hepatitis can also be spread through sexual contact, oral-fecal contact (directly or through food providers that didn't wash their hands), and unsafe blood transfusions. I wouldn't be terribly surprised if Arafat caught hepatitis in one of these ways.