Women in South Africa might be biologically predisposed to contracting HIV, explaining in part why local women are among the world’s most susceptible.
The US Centres for Disease Control estimates that, on average, a woman would have to have sex 1000 times with an HIV-positive male to get the virus. But this estimate does not hold in South Africa, particularly in rural KwaZulu-Natal (KZN), where more than half of pregnant women will be HIV-positive by the time they are 25 or older.
But research published by scientists at the Centre for the Aids Programme of Research in SA, show that KZN women who acquired HIV had more immune cells in their vaginas than those who did not. Salim Abdool Karim, the centre’s director, said: “This research provides evidence that the high HIV risk in women is not simply because of behaviour but has a biological basis.” This means that “in trying to reduce HIV in young women we might have been barking up the wrong tree by focusing only on trying to change their behaviour”.
The centre’s scientists have monitored thousands of KZN women for years, taking vaginal cell samples every six months for a range of HIV-prevention trials.
Their latest study reveals that 58 KZN women who contracted HIV had vaginas more “friendly” to the HI virus than women from the same community who had the same number of sexual partners and sexual encounters. After the women became HIV-positive researchers retrieved frozen genital cell samples taken from them before they became infected. These samples were compared to those from HIV-negative women in the same community.
Those who became HIV-positive had higher rates of genital inflammation, caused when the body’s immune system mobilises to fight an infection or other form of attack on the body. Inflammation causes large numbers of CD-4 (immune) cells to rush to an area to defeat the threat. These immune cells are the ones HIV infects. Karim said: “Something is causing an inflammatory response in the vagina, leading to an inflow of CD-4+ cells and thereby increasing the risk of HIV infection. “We have not yet found the cause of the inflammation.”
Sexually transmitted infections could not account for most of the inflammation found in the study. University of Cape Town researchers Jo-Ann Passmore and Lindi Masson, who took part in the research, said similar studies by them in other parts of South Africa showed the same results: inflammation in the vagina leading to a higher risk of contracting HIV. Masson is working on developing a test to detect inflammation of the vagina in the absence of symptoms.
Background. Women in Africa, especially young women, have very high human immunodeficiency virus (HIV) incidence rates that cannot be fully explained by behavioural risks. We investigated whether genital inflammation influenced HIV acquisition in this group.
Methods. Twelve selected cytokines, including 9 inflammatory cytokines and chemokines (interleukin [IL]-1α, IL-1β, IL-6, tumor necrosis factor-α, IL-8, interferon-γ inducible protein-10 [IP-10], monocyte chemoattractant protein-1, macrophage inflammatory protein [MIP]-1α, MIP-1β), hematopoietic IL-7, and granulocyte macrophage colony-stimulating factor, and regulatory IL-10 were measured prior to HIV infection in cervicovaginal lavages from 58 HIV seroconverters and 58 matched uninfected controls and in plasma from a subset of 107 of these women from the Centre for the AIDS Programme of Research in South Africa 004 tenofovir gel trial.
Results. HIV seroconversion was associated with raised genital inflammatory cytokines (including chemokines MIP-1α, MIP-1β, and IP-10). The risk of HIV acquisition was significantly higher in women with evidence of genital inflammation, defined by at least 5 of 9 inflammatory cytokines being raised (odds ratio, 3.2; 95% confidence interval, 1.3–7.9; P= .014). Genital cytokine concentrations were persistently raised (for about 1 year before infection), with no readily identifiable cause despite extensive investigation of several potential factors, including sexually transmitted infections and systemic cytokines.
Conclusions. Elevated genital concentrations of HIV target cell–recruiting chemokines and a genital inflammatory profile contributes to the high risk of HIV acquisition in these African women.