Welz T, Hosegood V, Jaffar S, Batzing-Feigenbaum J, Herbst K, Newell ML. Continued very high prevalence of HIV infection in rural KwaZulu-Natal, South Africa: a population-based longitudinal study. AIDS 2007 Jul 11;21(11):1467-72.
To estimate the prevalence of HIV and to assess its associated sociodemographic factors, including mobility and migration, in rural KwaZulu-Natal, South Africa.
This study is a household-based HIV serosurvey of a large, well-characterized rural population that has been under longitudinal demographic surveillance since 2000. Data on individuals' HIV-related risk factors and presence patterns were available for several years before the HIV serosurvey was carried out.
This study was conducted between June 2003 and November 2004 in the Africa Centre Demographic Surveillance Area in the rural district of Umkhanyakude in northern KwaZulu-Natal province, South Africa.
The two groups of individuals surveyed were "residents," defined as "individuals who report keeping their belongings and spending most nights at the surveyed household," and "non-residents" or "migrants," defined as "individuals whose residence is elsewhere but maintain connections with the household through periodic visits" Approximately 30% of all household members were non-resident or "migrants." All men aged 15-54 and all women aged 15-49 years recorded as residents on 18 June 2003 were eligible for the study; 12.5% of non-residents were randomly selected in equal numbers from each of 10 strata, defined according to sex and frequency of return visits to the area. A total of 28,889 residents (12,903 men and 15,986 women) were eligible for the HIV serosurvey, of whom 1,925 (7%) moved away or died; 191 (1%) aged out of eligible age range before a household visit; and 515 (2%) were lost to follow-up. Of the remaining individuals, 8,325 men (72%) and 11,542 women (80%) were traced. A total of 11,551 individuals - 4,692 men (56%) and 6,859 women (59%) - consented to HIV testing. A total of 2,009 non-residents were sampled, of whom 57 (3%) became ineligible due to death, severed links to the area, or "etc." (not specified in the study). Some 46% of these men (453/982) and 57% of these women (463/970) were successfully traced, of whom 257 men (57%) and 294 women (64%) consented to HIV testing.
Sociodemographic data were collected and updated through bi-annual household visits since January 2000. Between June 2003 and November 2004, trained fieldworkers made up to four attempts to visit all eligible individuals at home, and up to 10 attempts to track individuals who moved. Upon consent from eligible individuals, HIV testing was performed by finger prick and two antibody tests. Testing was "linked anonymous," but participants could access their results at community-based centers, and post-test counseling was made available to individuals who tested positive. No major HIV prevention or treatment studies were conducted among adults in the area before 2004, and the government treatment program began in September 2004.
The primary outcomes of this study were: 1) HIV prevalence in residents and non-residents; and 2) the effect of non-participation. For the latter outcome, multivariate analyses were used to compare sociodemographic characteristics with HIV infection and with non-participation in the study.
Of the 11,551 residents who consented to HIV testing, 13.5% of men and 27% of women were HIV-infected. HIV prevalence was highest at 51% [95% confidence interval, CI, 47-55%] among women aged 25-29 years and 44% [95% CI 38-49%] among men aged 30-34 years. The highest infection rate of 57.5% [95% CI 49-66%] was found among 26-year-old women. Overall, 21.5% of residents between the ages of 15-49 were HIV-infected. Among the 551 non-residents who consented to HIV testing, 34% of men and 41% of women were HIV-infected. HIV prevalence was highest at 63% [95% CI 50-76%] among women aged 25-29 years and 56% [95% CI 34-78%] among men aged 35-39 years. HIV infection was more prevalent in non-residents under 30 years of age for both men - 25% of non-residents compared with 6% of residents (p≤0.0001), and women - 40% of non-residents compared with 24% residents (p≤0.0001). The age-adjusted odds ratio for HIV infection among non-residents as compared with residents was 1.8 (95% CI 1.3-2.4) for men and 1.5 (95% CI 1.2-2.0) for women. Nine out of 12 sociodemographic factors were associated with increased risk of HIV infection: age, urban or peri-urban residence, living alone, earning an income, having electricity, having sanitation, being harder to trace, being away from the household for 10 or more nights in the preceding four months, and not attending school. These factors were also associated with non-participation for both men and women. Test refusers also generally had sociodemographic characteristics intermediate between those tested and those who were persistently absent.
The authors conclude that the extremely high prevalence of HIV suggests an urgent need to allocate adequate resources for HIV prevention and treatment in rural areas. Effective monitoring of the epidemic in Africa needs to include efforts to strengthen sentinel surveillance in rural areas and strategies for the surveillance of migrants and mobile individuals.
There is no quality rating system for population-based longitudinal studies. The study is likely of high quality since existing data from longitudinal demographic surveillance minimized the likelihood of problems such as errors with household listing and selection. A relatively high percentage of participants were tracked and tested; however, the potential for selection bias still exists.
This HIV serosurvey was the first of its kind in South Africa to investigate HIV prevalence in rural areas and its association with mobility and migration. It shows some of the highest population-based infection rates yet documented worldwide. High HIV prevalence has been reported by several other household surveys in South Africa: In 2003, 5% of men and 16% of women were reported to be HIV-infected.i The rates increased to 12% among men and 20% among women in 2005.ii The HIV prevalence of 21.5% found in this study is higher than the downsized 2005 UNAIDS estimate of 18.8%.iii Other studies suggest that cross-sectional surveys may underestimated HIV prevalence due to non-inclusion of mobile individuals,iv-vii and that absence during HIV surveys may represent passive refusal by high-risk individuals to participate.viii
Nearly half of the South African population lives in rural communities where migrant work is the norm ix,x and similar situations exist in other countries heavily affected by the HIV/AIDS epidemic. Accuracy of HIV surveillance in rural and migrant populations is therefore critical. The high HIV prevalence in young women and migrants is extremely concerning and indicates an urgent need to focus prevention and treatment efforts on these groups.
- Pettifor AE, Rees HV, Kleinschmidt I, Steffenson AE, MacPhail C, Hlongwa-Madikizela L, et al. Young people's sexual health in South Africa: HIV prevalence and sexual behaviors from a nationally representative household survey. AIDS 2005 Sep 23;19(14):1525-34.
- Shisana O, Rehle T, Simbayi LC, Parker W, Zuma K, Bhana A, et al. South African national HIV prevalence, HIV incidence, behaviour and communication survey, 2005. Cape Town: HRSC Press; 2005. (No abstract available.)
- Joint United Nations Programme on HIV/AIDS. 2006 Report on the global AIDS epidemic. Geneva: UNAIDS; 2006.
- Gregson S, Garnett GP. Contrasting gender differentials in HIV-1 prevalence and associated mortality increase in eastern and southern Africa: artefact of data or natural course of epidemics? AIDS 2000;14 Suppl 3:S85-99. Review. (No abstract available.)
- Nunn AJ, Kengeya-Kayondo JF, Malamba SS, Seeley JA, Mulder DW. Risk factors for HIV-1 infection in adults in a rural Ugandan community: a population study. AIDS 1994 Jan;8(1):81-6.
- Serwadda D, Wawer MJ, Musgrave SD, Sewankambo NK, Kaplan JE, Gray RH. HIV risk factors in three geographic strata of rural Rakai District, Uganda. AIDS 1992 Sep;6(9):983-9.
- Zaba B, Marston M, Isingo R, Urassa M, Ghys PD. How well do cross-sectional population surveys measure HIV prevalence? Exploring the effects of non-participation. In: XVth International AIDS Conference. Bangkok, Thailand, 11-16 July 2004 [Abstract LbOrC23].
- Calleja JM, Marum LH, Carcamo CP, Kaetano L, Muttunga J, Way A. Lessons learned in the conduct, validation, and interpretation of national population based HIV surveys. AIDS 2005 May;19 Suppl 2:S9-S17. Review.
- Census 2001. Pretoria: Statistics South Africa; 2003. Accessed: 18 August 2006.
- Lurie M. Migration and AIDS in Southern Africa: a review. South Africa J Sci 2000; 96:343-347.