Human Immunodeficiency Virus as a Sexually Transmitted Disease: Manitoba’s HIV Unlinked Seroprevalence Study

Objective: To determine the prevalence of human immunodeficiency virus (HIV)-1 infections.Design: An unlinked seroprevalence study on all ‘left over’ blood submitted for syphilis testing during three consecutive six month periods (April 1, 1990 to September 30, 1991). After the capture of demographic data, sera to be tested for antibodies were stripped of all personal identifiers and assigned a random number. The study fulfilled Canadian ethical guidelines.Participants: Persons with a valid Manitoba Health Services Commission number were included only once in a study year. Persons were enrolled into one of five categories: infants, injection drug users, pregnant women, persons investigated for sexually transmitted diseases (STD) and routine testing.Results: Of the 50,929 persons tested. 133 (0.26%) were positive, a low prevalence of HIV infections. A significant increase in positivity was noticed in the second study period. While 77.7% of those tested were women, only 10 (0.025%) were positive for HIV. The rate of positivity for pregnant women was 0.72 per 10,000 tested. Of the 11,314 males tested. 123 (1.08%) had antibodies. Most of the positives were males in the STD category residing in Winnipeg; for them, the rate of positivity increased by middle age, while the rate of testing decreased with each decade of age (from age 15 to 44 years).Discussion/Recommendation: This is the first report from a sentinel laboratory in Canada of an unlinked seroprevalence study in persons with STD. Results suggest an urgent need to target strategies for the control of HIV for persons with STD, particularly males in urban centres, by routine HIV testing for STD patients.