Sex, Lies, and AIDS in Africa

People cheat on their spouses and lie about it. Not exactly breaking news — except when it impacts the success of HIV policy for most of a continent. The increasingly couples-focused public-health policy for AIDS prevention in sub-Saharan Africa underestimated the role that sex outside of stable, cohabiting relationships plays in transmitting the virus, according to a new UC Berkeley–led study.

While cheating spouses are a known avenue for infection, previous studies found that extra-couple sex plays a small role in the HIV pandemic compared to transmission within “sero-discordant” couples, where one partner is infected with HIV and the other is not. Countries across Africa have chosen to adopt the strategy recommended by the World Health Organization to target sero-discordant couples, treating infected partners in order to protect the uninfected partner.

The new study, published in the February 4 early-online edition of The Lancet, found that transmission rates through extra-couple relationships are much higher than previous estimates had indicated.

“Our results suggest that extra-couple transmission has been and continues to be a relatively common contributor to new HIV infections,” said Steve Bellan, who led the study while working on his Ph.D. in environmental science, policy, and management at Berkeley and is now a postdoctoral researcher at the University of Texas at Austin. “We estimate that, of new HIV infections within stable, cohabiting couples, approximately half of the cases in men and one-third of the cases in women are due to extra-couple transmission.”

Measuring transmission routes is notoriously difficult. “Data comes from surveys, and you have to ask people rather sensitive questions and they are not necessarily going to answer accurately. What age are your partners? How many partners do you have? It’s very complicated and very difficult to get accurate data,” said Wayne Getz, a UC Berkeley professor of quantitative population biology and disease ecology and one of the study’s coauthors.

By contrast, this study, which used data from 18 African countries, minimized the use of sensitive survey data. “Our model disentangled routes of transmission, using only information on how long partners had been sexually active before entering their current relationship, how long they have been in the current relationship, the timing of these periods in relation to countrywide HIV prevalence trends, and whether partners were HIV-positive when surveyed,” said Bellan.

The researchers urge that public health strategies in Africa employ more broad-based efforts, such as public service messages encouraging regular testing for all sexually active adults, and increasing the availability of clinics that conduct testing, counseling, and treatment.

“We need to rethink the way we are approaching HIV policy and interventions in Africa,” Getz said. “You have to look at the population as a whole.”

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