Human herpesvirus 8 seropositivity and risk of Kaposi's sarcoma and other acquired immunodeficiency syndrome-related diseases

Background: The incidence of Kaposi's sarcoma (KS) is increased severalfold in individuals infected with human immunodeficiency virus-1 (HIV). Human h erpesvirus 8 (HHVS) has also been implicated in KS. We investigated several factors that may determine the onset of KS, particularly HHVS infection in individuals after becoming seropositive for HIV. Methods: We studied 366 i ndividuals belonging to different HIV-exposure categories (i.e., homosexual activity, intravenous drug use, and heterosexual contact) for whom a negat ive HIV serologic test and then a positive HIV serologic test were availabl e within a 2-year period. HHV8 antibody testing was performed by use of an immunofluorescence assay on the first serum sample available after the firs t positive HIV test. Actuarial rates of progression of KS and of other acqu ired immunodeficiency syndrome (AIDS)-defining diseases were estimated by u se of time-to-event statistical methods. All statistical tests were two-sid ed. Results: Twenty-one of the 366 study participants developed AIDS-relate d KS, and 83 developed AIDS without KS. One hundred forty (38.3%) participa nts had detectable anti-HHV8 antibodies. The actuarial progression rate to KS among persons co-infected with HIV/HHV8 was nearly 30% by 10 years after HIV seroconversion. Increasing HHV8 antibody titers increased the risk of developing KS (for seronegative versus highest titer [1 :125 serum dilution ], adjusted relative hazard [RH] = 51.82; 95% confidence interval [CI] = 6. 08-441.33) but not of other AIDS-defining diseases (adjusted RH = 1.14; 95% CI = 0.72-1.80). HHV8-seropositive homosexual men compared with HHV8-serop ositive participants from other HIV-exposure categories showed an increased risk of KS that approached statistical significance (adjusted RH = 6.93; 9 5% CI = 0.88-54.84). Conclusions: Approximately one third of individuals co infected with HIV/HHV8 developed KS within 10 years after HIV seroconversio n. Progression to KS increased with time after HIV seroconversion, Higher a ntibody titers to HHV8 appear to be related to faster progression to KS but not to other AIDS-defining diseases.