Graduate School of Public Health, San Diego State University, General Directorate of Epidemiology, Ministry of Health, California Department of Health Services, Viral and Rickettsial Disease Laboratory, San Diego California, Mexico
To assess the prevalence of human T cell lymphotropic virus type 1 and 2 (HTLV-1/2) infections among potentially high-risk populations in the city of Tijuana, Mexico, the prevalence of specific antibodies was determined and information on risk behaviors was obtained between June and October 1988. The study involved 631 presumably healthy individuals, randomly selected from a study population recruited sequentially from prisoners, prostitutes, and injecting drug users (IDUs), and randomly from homosexual and bisexual men. The presence of HTLV-1/2 antibodies was determined by enzyme immunoassay and an immunofluorescence method, and positive reactions were confirmed by a radioimmunoprecipitation assay and Western blot. The prevalence of HTLV-1/2 was 2% (2 of 105) among prostitutes, 7% (29 of 410) among prisoners, 1% (1 of 105) among homosexual/bisexual men, and 21% (22 of 106) among IDUs. To properly identify the specific HTLV type, a subsequent sample of 41 imprisoned IDUs were voluntarily and anonymously recruited in June 1990 and asked to donate 20 ml of whole blood. Twenty-two percent (9 of 41) were serologically positive for HTLV-1/2, and polymerase chain reaction analysis performed on peripheral blood mononuclear cells identified HTLV-2 as the specific virus prevalent in this group. Two individuals were positive for human immunodeficiency virus type 1 (HIV-1). One of these individuals was coinfected with HTLV-2. In view of the relatively high prevalence of HTLV-1/2 infection, we conclude that the potential for a rapid spread of HIV-1 infection exists in the city of Tijuana because of a high prevalence of high-risk practices such as unprotected sexual intercourse, drug abuse, and sharing of used needles among IDUs. Aggressive preventive measures should be implemented and binational cooperation and collaboration must continue.