Treatment of sexually-transmitted infections (STIs) and behavioural interventions are the main methods to prevent HIV in developing countries. We aimed to assess the effect of these interventions on incidence of HIV-1 and other sexually-transmitted infections.

We randomly allocated all adults living in 18 communities in rural Uganda to receive behavioural interventions alone (group A), behavioural and STI interventions (group B), or routine government health services and community development activities (group C). The primary outcome was HIV-1 incidence. Secondary outcomes were incidence of herpes simplex virus type 2 (HSV2) and active syphilis and prevalence of gonorrhoea, chlamydia, reported genital ulcers, reported genital discharge, and markers of behavioural change. Analysis was per protocol.

Compared with group C, the incidence rate ratio of HIV-1 was 0·94 (0·60–1·45, p=0·72) in group A and 1·00 (0·63–1·58, p=0·98) in group B, and the prevalence ratio of use of condoms with last casual partner was 1·12 (95% CI 0·99–1·25) in group A and 1·27 (1·02–1·56) in group B. Incidence of HSV2 was lower in group A than in group C (incidence rate ratio 0·65, 0·53–0·80) and incidence of active syphilis for high rapid plasma reagent test titre and prevalence of gonorrhoea were both lower in group B than in group C (active syphilis incidence rate ratio, 0·52, 0·27–0·98; gonorrhoea prevalence ratio, 0·25, 0·10–0·64).

The interventions we used were insufficient to reduce HIV-1 incidence in rural Uganda, where secular changes are occurring. More effective STI and behavioural interventions need to be developed for HIV control in mature epidemics.