3.1.6 HIV incidence and prevalence trends in a rural cohort, Masaka district: Medical Research Council (MRC) Programme on AIDS.

The MRC-supported observational cohort study undertaken in 15 villages in rural Masaka District, and started in 1989, has provided considerable information on HIV dynamics in rural settings. This study provided the first evidence of decreasing HIV-1 sero-prevalence in young adults. From 1990-94 HIV sero-prevalence in males 13-24 decreased from 3.4% to 1% and in females 13-24, from 9.9% to 7.2%, while overall cohort prevalence was stable, 8.2% in 1990 and 7.2% in 1994 (BMJ 31 30 Sept. 1995). More recent cohort data (Lancet. Sept. 1996) on sero-incidence suggest an increase in HIV infections in females aged 13-34 from 0.6% in 1990 to 1.2% in 1994, but declines in older females and in males. The incidence rates are so low that meaningful trends in age-specific rates are illusive (13-34 is a very broad age group), but in discussion with Dr Whitworth in late February, he agreed to supply these data as well as the latest prevalence data for the cohort by mid-April.

The apparent stability (or even increase) in prevalence and possibly incidence rates, in this rural population contrasts with the declines observed among urban and semi-urban populations and suggests that distinct HIV behavioural dynamics are at work in rural populations. Behavioural surveys suggest that greater behaviour changes have occurred in urban than rural people, and also supports the contention that sexual behaviour patterns may be more amenable to aggressive promotion of preventive strategies and interventions than had been previously thought possible or likely. Further population based KABP surveys of this population would offer an important and much more precise link with data on sero-incidence and prevalence.

NB. Data from Masaka was not available by mid-May, but should be pursued by USAID Uganda.