Co-infection with HIV-1/HTLV-II and the risk of progression to AIDS and death. The Oslo HIV Cohort Study Group.

Human T-cell lymphotropic virus (HTLV) types I and II were the first discovered human retroviruses. While HTLV-I has been clearly associated with disease, the health implications of HTLV-II infection are still unsettled. A prospective epidemiological study of 409 HIV-infected subjects of different transmission categories was performed to study the presence of HTLV-II antibodies, and whether HTLV-II antibodies are associated with the progression to AIDS and to death of any cause. Of 409 subjects, 30 (7.3%) were HTLV-II positive at study entry; 2 subjects seroconverted during follow-up. In the HTLV-II-positive group 2 were heterosexually HIV infected, 28 (of whom 2 were seroconverters) were IDUs and 2 were homosexual men. When controlling for transmission category, gender, age and CD4+ lymphocyte count at study entry, the relative risk of AIDS progression for the HTLV-II-positive group was 2.1 (0.8-5.1, 95% confidence interval (CI)) as compared to the HTLV-II-negative group. The adjusted relative risk of dying was 2.1 (1.0-4.3, 95% CI). When studying IDUs separately, the adjusted relative risk of AIDS progression was 2.3 (0.8-6.9, 95% CI) and the relative risk of dying was 2.0 (0.9-4.6, 95% CI). The results of this study suggest that HTLV-II is a cofactor in HIV disease progression. The number of HTLV-II-infected subjects, was, however, small, and insufficient control of confounding factors must be taken into consideration.