The social dynamics of HIV transmission as reflected through discordant couples in rural Uganda

To describe the role of men and women as sources of HIV transmission and to estimate HIV incidence among discordant couples resident in diverse rural communities in Uganda.

Rakai, a rural district in Uganda, East Africa.

A population-based cohort study, which has been conducted as annual serological and behavioral surveys since 1989. Community clusters were stratified into trading centers on main roads, intermediate trading villages on secondary roads and agricultural villages off roads. In the 1990 survey round, serological data were available for 79 discordant and 411 concordant HIV-negative couples aged 13-49 years. The present analysis examines sex-specific seropositivity associated with place of residence and the incidence of seroconversion among discordant couples between 1990 and 1991.

Seventy-nine discordant couples were followed; the HIV-positive partner was male in 44 couples (57%) and female in 35 couples (43%). There was marked variation in the sex of the seropositive partner by place of residence: women were the HIV-positive partner in 57% of couples from trading centers, 52% from intermediate villages, and 20% from agricultural communities (P < 0.008). Condom use was higher in discordant couples in which the man was the uninfected partner (17.1%) rather than the woman (9.5%). HIV-positive women, but not HIV-positive men, reported significantly more sexual partners and more genital ulcers than seronegative individuals of the same sex. Seroincidence rates among men and women in discordant relationship were 8.7 and 9.2 per 100 person-years (PY), respectively, which was much higher than in concordant seronegative couples (men, 0.82; women, 0.87 per 100 PY).

In this Ugandan population, men are the predominant source of new infections in rural villages. Risk factors and preventive behaviors vary with the sex of the infected partner, and seroconversion rates are similar in both sexes.