Risk factors for HTLV-I and II in individuals attending a clinic for sexually transmitted diseases

Background: To date, few studies have provided information on risk factors for human t-lymphotropic viruses (HTLV) types I and II in European countrie s. In particular, few data are available from published studies conducted i n STD centers. Goals: To identify risk factors for HTLV-I and HTLV-II infection and to bet ter distinguish the epidemiologic patterns of the two viruses in Italy. Study Design: A cross-sectional study of individuals at high risk of sexual ly or parenterally transmitted infections attending a large STD center in a n urban setting was conducted. Serologic tests for HTLV-I and II, HIV, hepa titis virus type B (HBV), hepatitis virus type C (HCV), and syphilis were p erformed. Information regarding at-risk behavior was collected using a spec ific questionnaire. Results: From January 1994 to June 1996, 1,457 individuals were recruited; of them, 1,016 (69.7%) were males, 1,051 (72.4%) Italians, and 288 (19.8%) non-Europeans. One thousand seventy-five (74.8%) participants were noninjec ting-drug-using heterosexuals, 285 (19.6%) were men who have sex with men, and 97 (6.6%) were injecting drug users (IDU). The mean age of the study pa rticipants was 33.6 (+/-10.5) years. Nine (0.6%) individuals were positive for HTLV-I antibodies and 9 (0.6%) for HTLV-II antibodies. The prevalence o f HTLV-I among IDUs, men who have sex with men, and noninjecting-drug-using heterosexuals, was 2.1% (2/97), 1.4% (4/285), and 0.3% (3/1085), respectiv ely. HTLV-II prevalence was 8.2% (8/97) among IDUs and 0.09% (1/1075) among noninjecting-drug-using heterosexuals. Among the nine HTLV-II-positive ind ividuals, eight were Italian IDUs and one was a noninjecting-drug-using het erosexual man from India. None of the 285 men who have sex with men had HTL V-II antibodies. HTLV-infected individuals tended to be older than those wh o were uninfected, HTLV-I-infected individuals were more likely to be non-E uropean and to have antibodies against Treponema pallidum. Injecting drug u se tended to be independently associated with HTLV-II infection. Conclusions: The data suggest a role of sexual behavior in the spread of HT LV-I, which is more likely to be detected in individuals coming from endemi c areas. Injecting drug use remains the most important risk factor for HTLV -II infection in Italy.