RESUMEN
BACKGROUND: Dual infection with diverse HIV strains can foster the emergence of recombinants. The resulting increase in viral genetic diversity is a major challenge for vaccine development HIV treatment. In this study we aim to investigate the socio demographic factors associated with an increasing level of genetic diversity among HIV strains in a population of drug-users in Northern Thailand. METHODS: From 1999 through 2000, 2231 volunteers were enrolled in the Opiate-Users Research in Chiang Mai, Thailand. HIV subtype analysis was conducted among those HIV-1 seropositive (n=347) using a multi-region hybridization assay. Social and demographic variables were assessed using a structured questionnaire. RESULTS: Overall, 336/347 (96.8%) of the samples could be typed. 81.8% were CRF01_AE, 3.9% were subtype B, 9.2% were recombinants (mostly between CRF01_AE and B) and 5.1% were dual infections. Dual infections were more frequent among those with a lower education level (AOR: 5.2; 95% CI 1.4-20.3), those who have initiated injecting in the last 3 years (AOR: 3.9; 95% CI 1.1-14.6), and those reporting frequent needle sharing in the last 3 months (AOR: 7.0; 95% CI 1.5-34.1). Both recombinant strains and dual infection were more frequent among those reporting frequent needle sharing in the last 3 months (AOR: 5.3; 95% CI 1.6-17.1). CONCLUSION: To limit the expanding complexity of HIV-1 strains, early intervention should be aimed at reduction in needle sharing, especially among new intravenous drug users.