Evidence for concurrent epidemics of human herpesvirus 8 and human immunodeficiency virus type 1 in US homosexual men: rates, risk factors, and relationship to Kaposi's sarcoma.

We examined human herpesvirus 8 (HHV-8) seroprevalence and seroincidence among 245 homosexual men from New York City (NYC) and Washington, DC (DC) who have been followed since 1982. An immunofluorescence assay measured antibodies to a latent HHV-8 nuclear antigen. Seroprevalence was 20.4% in 1982; seroincidence was approximately 15%/year during 1982-1983 but fell sharply thereafter. NYC men had a higher seroprevalence (odds ratio, 3.43; P<.001) and seroincidence (rate ratio, 2.13; P=.01) than DC men. Risk of Kaposi's sarcoma (KS) was increased in seropositive men (adjusted relative hazard, 3.58; P=.02). Among men who were seropositive for both human immunodeficiency virus type 1 and HHV-8, the 10-year cumulative risk of KS was 39%; time from coinfection to KS diagnosis ranged from 15 to 154 months (median, 63.5 months). This study shows an epidemic of HHV-8 among US homosexual men in the early 1980s that was associated with a high risk of developing KS.