Interventions that target individuals with a high risk of contracting HIV have a negligible impact on HIV transmission in the general population, according to a new study of communities in Zimbabwe, published today. The three-year study shows that community-based peer education, free condom distribution, and clinic-based STI treatment and counselling services targeted at female sex workers and their male clients had no impact on HIV incidence in the wider community.
The study shows that it was possible to reduce the incidence of HIV in men - but not the women - who were reached by the programme. However, the reduction in HIV incidence amongst these men did not have the anticipated impact on HIV incidence in the larger community.
The researchers, writing in the journal PLoS Medicine, had hoped that levels of HIV in the community as a whole could be reduced through targeting men and women who were perceived to have the riskiest sexual behaviour and reducing the incidence of HIV amongst them. They believed that this would reduce HIV incidence in the wider sexual networks where these people were thought to be key.
The programme aimed to reduce transmission through sex workers and it provided women with small interest-free loans together with training in small business management, in order to reduce their economic dependence on sex work. Recent studies show that commercial sex work centred around bars and beer halls remains a major source of HIV transmission.
The male participants benefited from the programme with a decrease in incidence of HIV-1, a reduction in reporting of unprotected sex with casual partners, and a decrease in symptoms of sexually transmitted infections. However, the study found that these benefits were not shared by the sex workers reached by the programme and there was no resultant reduction in HIV incidence for the community as a whole.
The researchers believe that their efforts to reduce incidence in female sex workers were unsuccessful largely for economic reasons. Whilst some men may have given up visiting sex workers or started to use condoms consistently, the sex workers themselves were unable to acquire alternative sources of income and continued to have unprotected sex with some of their partners - on occasions, in exchange for a larger payment.
Dr Simon Gregson, lead author of the study from the Department of Infectious Disease Epidemiology at Imperial College London, said: "The results of the study were disappointing. Targeting smaller high-risk groups did not have the knock-on effect we had hoped and in addition, we weren't able to reduce the incidence of HIV in women in the way we had anticipated. We wanted to reduce women's reliance on sex work through our micro-credit scheme but this failed, partly because of the economic downturn in Zimbabwe.
"Programmes similar to the one we introduced are widely used in HIV prevention in sub-Saharan Africa. Our study shows that we probably need much larger programmes, based on skills training, to alleviate poverty and strategies that reach into the wider community to stem the epidemic," he added.
The study compared six pairs of communities in Eastern Zimbabwe, each with its own health centre. Control communities received the standard government services for preventing HIV. The other communities received a package of additional strategies including education and condom distribution amongst sex workers and their clients; better services at sexually transmitted infection clinics; and educational HIV/AIDS open days at health centres. Over 63,000 meetings were conducted and 7 million condoms were distributed by trained peer educators.
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