HIV prevalence by race co-varies closely with concurrency and number of sex partners in South Africa

Abstract

Background: HIV prevalence differs by more than an order of magnitude between South Africa's racial groups. Comparing the sexual behaviors and other risk factors for HIV transmission between the different races may shed light on the determinants of South Africa's generalized HIV epidemic.

Methods: Five nationally representative and one city-representative population-based surveys of sexual behavior were used to assess the extent to which various risk factors co-varied with HIV prevalence by race in South Africa.

Results: In 2004, the prevalence of HIV was 0.5%, 1%, 3.2% and 19.9% in 15-49 year old whites, Indians, coloureds and blacks respectively. The risk factors which co-varied with HIV prevalence by race in the six surveys were age of sexual debut (in five out of five surveys for men and three out of six surveys for women), age gap (zero surveys in men and three in women), mean number of sex partners in the previous year (five surveys in men and three in women) and concurrent partnerships (five surveys in men and one in women). Condom usage and circumcision were both more prevalent in the high HIV prevalence groups. The reported prevalence of concurrency was 6 to 17 times higher in the black as opposed to the white men in the five surveys.

Conclusions: The differences in sexual behavior in general, and the prevalence of concurrency and the number of sexual partners in particular, offer a plausible and parsimonious cause to explain a part of the differing prevalences of HIV between South Africa's racial groups.

Figure 1. Prevalence of sexual behaviors, condom use and circumcision by race and sex in five South African surveys of 15–49 year olds.

Mean age of sexual debut (A,B), Age gap – the percentage of respondents with a partner five (ten in the case of DHS 2003) or more years older than them (C,D), Mean number of sex partners in the past year (E,F), Percent of respondents who had more than one sex partner in the previous year (G,H), Percentage respondents who used a condom at last sex (I,J), Percent respondents who reported concurrent relationships at the time of the interview (K,L), Percent of men who reported having been circumcised (M). Men and women represented in the left and right hand columns respectively (Point estimates with 95% Confidence Intervals. A,B and M refer to all respondents and C–L to those who have had sex). DHS (Demographic and Health Survey) 1998 and 2003, SABSSM (South African National HIV Prevalence, HIV Incidence, Behavior and Communication Survey) 2002 and 2005, NCS (National Communication Survey) 2009.