HTLV-II and bacterial infections among injection drug users

Objective: To examine whether select bacterial infections are associated with HTLV-II infection among injection drug users, we conducted a nested case control study within an ongoing cohort study. Method: HTLV-II status was determined by enzyme-linked immunosorbent assay, immunofluorescent assay, and immunoblot. Diagnosis of bacterial pneumonia, infective endocarditis, and skin abscess was confirmed by standardized chart reviews. Three sets of cases were identified based on diagnosis of bacterial pneumonia, infective endocarditis validated by chart review, or self-reported skin abscess. Each case was matched to a minimum of 5 controls by age, HIV status, and study follow-up duration. Risk factors for each bacterial infection were analyzed separately by conditional logistic regression methods. Results: Prevalence of HTLV-II infection ranged from 7% to 11% in cases and controls. The bivariate association of HTLV-II and bacterial pneumonia revealed an odds ratio (OR) of 1.1 (95% confidence interval [CI], 0.6-2.0); the association of infective endocarditis and HTLV-II revealed an OR of 1.7 (95% CI, 0.7-3.9); and the association between HTLV-II and skin abscess revealed an OR of 1.3 (95% CI, 0.6-2.0). These ORs were unaltered by adjustment for other factors. Conclusion: Our results suggest that these three bacterial infections were not significantly associated with HTLV-II infection within a population of injection drug users. Additional associations between HTLV-II infection and disease outcomes merit further exploration.