In the late 1980s, hemophiliacs were transfused with a variety of blood products, including large amounts of cryoprecipitate. In comparison to other cohorts, hemophiliacs are CMV(-), resulting in a comparison group for the study of this virus as a potential cofactor. In contrast, non A, non-B hepatitis is common in comparison to other cohorts, and preliminary data prior to 1990 suggested that this chronic disease predisposes to more rapid progression of HIV infection.