Understanding the Uneven Spread of HIV within Africa: Comparative Study of Biological, Behavioral and Contextual Factors in Rural Populations in Tanzania and Zimbabwe

Author(s): Boerma J T, Nyamukapa C, Urassa M, Gregson S

Year: 2002

Abstract:
Objective: To identify factors which explain differences in the spread of HIV between rural sub-Saharan African populations. Methods: Ecological comparison of data from cross-sectional population-based HIV surveys in high and relatively low HIV prevalence rural areas in Zimbabwe (Manicaland) and Tanzania (Kisesa). Results: HIV prevalence in Manicaland and Kisesa was 15.4% (n = 1,624) and 5.3% (n = 2,588) in men aged 17-44 years (odds ratio [OR] 3.3; 95% CI, 2.6-4.1) and 21.1% (n = 2,968) and 8.0% (n = 3,365) in women aged 15-44 years (OR, 3.1; 95% CI, 2.7-5.7). Marriage is later, spatial mobility more common, cohabitation with marital partners less frequent, education levels are higher, and male circumcision is less common in Manicaland. However, adjustment for differences in these factors increased the odds ratios for HIV infection in Manicaland versus Kisesa to 6.9 (95% CI, 4.9-9.8) and 4.8 (95% CI, 3.6-6.3) for men and women, respectively. STI levels were similar but syphilis was only common in Kisesa. Respondents in Kisesa started sex earlier and reported more sexual partners, while age differences between partners were similar. Conclusion: The comparison of data on a wide range of underlying and proximate factors for the rural populations has resulted in few possible reasons for the much more extensive spread of HIV in Zimbabwe. The most important differences between the two populations pertained to underlying socio-demographic variables, such as the much lower levels of spousal cohabitation and the higher levels spatial mobility seen in Manicaland, although these differences did not translate into changes in reported sexual behavior. Key Words: HIV prevalence - Epidemic size - Ecological study - Proximate determinants - Tanzania - Zimbabwe