Prevalence of antibodies to HTLV-I, -II, and -III in intravenous drug abusers from an AIDS endemic region.

Antibody prevalences for human T-cell lymphotropic virus (HTLV) types I, II, and III were determined for 56 intravenous drug abusers from Queens, NY. While control serum samples lacked antibodies to all HTLV subgroups, seropositivity among drug users was 41% for HTLV-III, 18% for HTLV-II, and 9% for HTLV-I. Infection by HTLV-I and -II occurred independently of HTLV-III infection. Blacks had greater HTLV-III antibody prevalence than whites (54% vs 16%) and were more likely than whites to be seropositive for HTLV-I or -II (46% vs 11%). They exhibited a greater incidence than whites of double infection with HTLV-I or -II and HTLV-III (27% vs 0%), and 73% were seropositive for at least one of the viruses, compared with only 26% of the whites. The increased HTLV-I and -II infection seen in intravenous drug users suggests that once introduced into a population, these viruses may be transmitted by the same routes as HTLV-III. Transmission may have been restricted mainly to blacks in this study because of local drug use practices.