Declining HIV prevalence and risk behaviours in Zambia: evidence from surveillance and population-based surveys

Objective: To examine trends in HIV prevalence and behaviours in Zambia dur ing the 1990s. Methods: The core Zambian system for epidemiological surveillance and resea rch has two major components: (i) HIV sentinel surveillance at selected ant enatal clinics (ANC) in all provinces; and (ii) population-based HIV survey s in selected sentinel populations (1996 and 1999). The former was refined in 1994 to improve the monitoring of prevalence trends, whereas the latter was designed to validate ANC-based data, to study change in prevalence and behaviour concomitantly and to assess demographic impacts. Results: The ANC-based data showed a dominant trend of significant declines in HIV prevalence in the 15-19 years age-group, and for urban sites also i n age-group 20-24 years and overall when rates were adjusted for over-repre sentation of women with low education. In the general population prevalence declined significantly in urban women aged 15-29 years whereas it showed a tendency to decline among rural women aged 15-24 years. Prominent decline in prevalence was associated with higher education, stable or rising preval ence with low education. There was evidence in urban populations of increas ed condom use, decline in multiple sexual partners and, among younger women , delayed age at first birth. Conclusions: The results suggested a dominant declining trend in HIV preval ence that corresponds to declines in incidence since the early 1990s attrib utable to behavioural changes. Efforts to sustain the ongoing process of ch ange in the well-educated segments of the population should not be underval ued, but the modest change in behaviour identified among the most deprived groups represents the major preventive challenge. (C) 2001 Lippincott Willi ams & Wilkins.