Estimation of the sexual transmission of HIV in Kenya and Uganda on the trans-Africa highway: the continuing role for prevention in high risk groups

Abstract

Objective: To explore the effect of transactional sex on the trans-Africa highway from Mombasa-Kampala in contributing to the HIV epidemic and the impact that an effective prevention intervention could have.

Methods: Variables for input into a simple model of HIV prevention, AVERT, were derived from a study of hot spots of transactional sex on the trans-Africa highway. Diaries were completed by a sample of sex workers at selected sites of transactional sex for a period of 28 consecutive days. Key information elicited included numbers, types and occupations of clients, numbers of liaisons, sexual acts in each liaison, and condom use. 857 diaries were distributed and 578 received and usable in 30 sites. A sexual patterning matrix was completed by 202 truckers at the Malaba border point as part of a health seeking behaviour survey. Two methods were employed to estimate female sex worker (FSW) numbers on the highway. FSW focus group discussions (FGDs) at 15 sites were carried out and included questioning on the number of sex workers at the site. As most transactional sex on the highway is centred on bars and lodgings, a patron census and survey of 1007 bars and lodgings was carried out which included questions on the presence and proportions of FSWs among the clientele.

Results: There are an estimated 8000 FSWs on the trans-Africa highway from Mombasa to Kampala. Annual numbers of different sexual partners per FSW were 129, annual numbers of sexual acts per FSW were 634, percentage of sexual acts protected by condom use was 77.7%. Using these input data an estimated 3200-4148 new HIV infections occur on this portion of the trans-Africa highway in 1 year. Having a 90% condom use programme in place could prevent almost two thirds of these infections and cumulative incidence would decline from 1.29% to 0.42%.

Conclusions: In generalised epidemics there has been a debate as to the place of targeted interventions. In the current east African epidemic we show that a targeted intervention could have significant impact in averting HIV infections related to the trans-Africa highway.