Bacterial vaginosis and susceptibility to HIV infection in South African women: A nested case-control study

Background. Bacterial vaginosis ( BV) may increase women's susceptibility to HIV infection, but there are few prospective data. Methods. During follow-up for up to 36 months, 86 new HIV seroconverters ( case patients) were identified among 5110 women enrolled in a cervical cancer screening trial. Nonseroconverting control subjects (n = 324) were frequency matched to case patients by age and duration of follow-up. At enrollment, case patients and control subjects were evaluated for clinical signs of BV, and Gram stains of vaginal fluid were scored using Nugent criteria. Results. BV was diagnosed on the basis of clinical criteria at enrollment in 20% of seroconverters and 16% of control subjects ( summary odds ratio [ OR], 1.31 [ 95% confidence interval {CI}, 0.71-2.41]). Nugent criteria for BV were met by 74% of seroconverters and 62% of control subjects. Diagnosis of BV on the basis of Nugent criteria was significantly associated with an increased risk of HIV seroconversion, after adjustment for demographic characteristics, other sexually transmitted infections, and sexual behaviors ( adjusted OR, 2.01 [ 95% CI, 1.12-3.62]). Conclusions. BV may account for a substantial fraction of new HIV infections in this setting. Treatment of BV and other interventions to promote normal vaginal flora warrant attention for HIV prevention.