Impact and Process Evaluation of Integrated Community and Clinic-based HIV-1 Control: a Cluster-randomised Trial in Eastern Zimbabwe

Background and Literature Review

The Spread and Early Demographic Impact of HIV in Zimbabwe

High levels of HIV prevalence and incidence have been recorded in Zimbabwe since sentinel surveillance was introduced in 1990. Prevalence levels in excess of 40% have been recorded among women attending antenatal clinics in a number of urban centres [1,2]. In a cohort study of male factory workers conducted in Harare between 1993 and 1995, 19% of participants were found to have the infection at enrolment and an incidence rate of 2.93% per annum was recorded [3]. However, rural areas - where 70% of the country's population are based - are experiencing some of the highest rates of incidence at the current time. In Mberengwa, Midland Province, HIV prevalence among pregnant women increased from under 8% in 1992 to 25% in 1994 [4].

In a study in two rural areas of Manicaland Province, we also found high levels of HIV infection at antenatal clinics in 1993-94 - 24% and 14%, at the growth points in the Honde Valley and the Rusitu Valley, respectively. Further data from the Honde Valley in 1996 indicate that incidence remains high (2-4%). Significant increases in adult and infant mortality and in orphanhood were recorded. The cause-specific and age-patterns of increase indicate that these are due primarily to HIV infections. Sexual intercourse with casual partners is common and condom use is low. In qualitative studies, high proportions of men, but relatively few women, reported recent casual partnerships. Mathematical model simulations indicate that this pattern of behaviour could explain the greater excess mortality that was recorded among males, given a recent - last 4-5 years - escalation of the HIV epidemic in rural areas. Other ulcerative and non-ulcerative sexually transmitted diseases (STDs) are common, but only 2% of respondents were aware that STDs can facilitate HIV transmission [5 8].

Mathematical model projections, based on our understanding of the predominant behaviour pattern and fitted to observed trends in HIV prevalence, also indicate that further increases in adult and early childhood mortality are to be expected. Results from these simulations and empirical findings from Uganda suggest that these increases will result in adverse indirect effects, including high proportions of children experiencing orphanhood and distortions in the age- and sex-distribution of the population [9,10]. These effects may be compounded by fertility change. Birth rates are declining in rural areas of Zimbabwe at present and the HIV epidemic may re-enforce this decline through changes in behaviour or underlying fecundity [11]. Women with HIV infection are reported as having lower fertility than other women in Ugandan studies [12] and results from our research in Manicaland indicate that behaviour changes which would tend to re-enforce the existing decline in birth rates may be beginning to occur [7].