In Africa, STI testing could boost HIV prevention
To maximize HIV prevention efforts in South Africa and perhaps the broader region, public health officials should consider testing for other sexually transmitted infections when they test for HIV, according to a new paper in the journal Sexually Transmitted Infections.
STIs can make HIV easier to transmit even after antiretroviral therapy has begun, so rooting out STI co-infections in patients should improve HIV prevention. The new study led by Brown University public health researchers emphasizes that sooner is indeed better than later, because the data show that HIV-positive South Africans were much more likely to be troubled by STIs before starting HIV treatment than after.
Originally in the study, which was a review of medical records of more than 1,400 HIV-positive Cape Town city clinic patients, the researchers were looking to see whether people already on antiretroviral therapy were subsequently contracting STIs that could undermine the HIV-prevention benefits of their treatment. But when they looked at the patients' histories, they found that the time when most people contracted STIs was well prior to starting the drugs.
"Once people get on antiretroviral treatment, STI's become less prevalent," said Mark Lurie, assistant professor of epidemiology at Brown University and lead author, whose research team included graduate student Kirwa Kipruto. "It's really the period prior to that that's especially important."
Specifically, among the 1,465 HIV-positive patients who agreed to take part in the study, 131 people sought STI treatment in a total of 232 incidences (some people sought care multiple times). More than 87 percent, or 203, of the incidences occurred before the patients received antiretroviral treatment, or ART. Controlling for other potential confounders, the researchers found that people on ART were seven times more likely to seek treatment for a sexually transmitted infection in the period prior to ART compared to the period on ART.
Lurie said the study does not explain why people are much less likely to need STI treatment after beginning HIV medicines. It could be a change in sexual behavior or an effect of the drugs itself.
The broader population
Lurie's greatest concern is not so much about the individual patients in the study. They all sought and received care in Cape Town's network of 78 clinics. His worry is about what the data from this sample may suggest about millions of sub-Saharan Africans whose infections are as yet undiagnosed. When they are tested for HIV, he said, the data suggest they should also be tested for other STIs to make their treatment the most effective it can be.
"There's a whole population of people out there right now who may or may not know about their HIV infection status, have a co-infection with an STI and are highly likely to transmit both HIV and their co-occurring STI to a sexual partner," he said.
It's also not so important whether co-infected people acquired HIV or the other STI first, Lurie said. A system focused on detection of co-infection when it is most prevalent can reduce HIV transmission more effectively.
"The high rates of STIs that we observed among people already infected with HIV during the period prior to antiretroviral therapy initiation represents an important opportunity for prevention and suggests a more comprehensive approach to HIV transmission is needed beyond ART," Lurie, Kipruto and their colleagues conclude in the paper. "Systematically including STI detection and treatment in the standard of care for people living with HIV will likely result in both a reduction in further transmission and increased viral suppression once people are on ART."