Increased hepatitis C virus load among injection drug users infected with human immunodeficiency virus and human T lymphotropic virus type II

Coinfection of hepatitis C virus (HCV) and human immunodeficiency virus (HIV) and/or human T-lymphotropic virus type II (HTLV-II) is common among drug users. We compared HCV RNA detection and load in a cohort of 6570 injection drug users from 9 US cities during 1987-1991. Of 385 subjects selected from 16 strata by sex, race (black or nonblack), and HIV/HTLV-II group (HIV positive [HIV⁺]/HTLV-II⁺, HIV⁺/HTLV-II negative [HTLV-II^-], HIV^-/HTLV-II⁺, and HIV ^-/HTLV-II^-), 376 had HCV antibodies, of whom 305 had detectable HCV load. HCV RNA detection was unrelated to sex, race, and virus groups, but differed by study site. The mean HCV load was 5.4 log₁₀ IU/mL and was 0.24 log₁₀ higher in men than in women. Virus load increment with HIV or HTLV-II infection was higher among white subjects than among other subjects. Compared with HIV^-/HTLV-II^- subjects, virus load was 0.50, 0.22, and 0.56 log₁₀ higher in HIV⁺/HTLV-II^-, HIV^-/HTLV-II⁺, and HIV⁺/HTLV-II⁺ subjects, respectively. HTLV-II infection significantly increased HCV load in white subjects but not in other racial groups.