An overgrowth of a particular bacteria found in some women’s vaginas might be one of the reasons South African women contract HIV so easily.
South African women have among the highest rates of HIV infection in the world and they are more likely to get infected having unprotected sex with an HIV-positive man than are women in other parts of the world.
Until now researchers were unable to say why this was the case, but now a team led by Salim Abdool-Karim, director of the Centre for the Aids Programme of Research in SA,discovered that KwaZulu-Natal women who had a proliferation of Prevotella bivia bacteria in their vaginas were 13 times more likely to contract HIV during sex.
The bacteria is not sexually transmitted and it is not known why some women have it and others don’t.
The researchers studied HIV- negative vaginal samples from 119 women in Vulindlela in KwaZulu-Natal to find clues about why some women got HIV and others didn’t.
They discovered in the women who became infected that some had too much of particular type of Prevotella bivia bacteria.
“Contracting HIV is not simply a matter of behaviour or biology only, but a combination of the two,” said Karim.
This understanding is helpful because it gives policy-makers a clue on how to better prevent new HIV infections.
It also means that if women with this bacteria are more predisposed to HIV, a simple cheap test to detect it and an antibiotic to eradicate the bacteria could reduce the risk of contracting HIV.
“While many biological features of the vagina that make women susceptible to infection cannot be changed, its microbiome could potentially be modified.
“We can change the types of bacteria that colonise the vagina.
“This could lead to ways of improving the effectiveness of prevention strategies,” said Anthony Fauci, director of the National Institutes of Allergy and Infectious Diseases at the US National Institutes of Health.
Karim said the research needed to be confirmed in other groups of women.
In another study conducted by Karim and his team, they found a different type of bacteria in the vagina was destroying a Tenofovir gel, which is used inside the vagina to prevent HIV transmission.
This could explain why many trials of Tenofovir gel have been unsuccessful in South Africa.