Seroprevalence and demographic characteristics of injection drugs users among individuals at risk for HIV infection in Winnipeg, Manitoba, Canada.

From June 1986 to March 1990, a prospective seroprevalence survey and questionnaire of individuals at risk for HIV infection was conducted with volunteers in Winnipeg. Of 610 individuals enrolled, 146 were injected drug users (IDU). Fifteen IDU were in a methadone treatment program and all were seronegative. Three of 131 remaining IDU were HIV-1 seropositive (2.3%), a rate similar to 2.2% positive (20+ of 927) in diagnostic specimens from IDU tested in the province. Demographics and behaviour of 131 IDU were compared with 335 individuals, of whom 112 were gay/bisexual [24 of whom also had sexually transmitted diseases (STD)] and 223 heterosexuals who had STD. Males enrolled were significantly older than females. Multivariate analysis showed that factors independently associated with IDU were: a younger age, less education, mental health counselling, unemployment, and a history of jaundice or hepatitis. Drugs most commonly used were Ritalin/Talwin, cocaine, and heroin. Over 90% of individuals admitted to sharing needles. In spite of the low seroprevalence of HIV-1 infections, these individuals are important for the potential spread of HIV because of multiple means of acquiring and transmitting HIV and a high rate of needle sharing.