The puzzle of Africa's HIV and AIDS rates.

The puzzle of Africa's HIV and AIDS rates.

The puzzle of Africa's HIV and AIDS rates.

Health and medicine explained.
May 15 2007 3:00 PM

Sex Nets

The puzzling rise and fall and rise of HIV and AIDS in Africa.

The Invisible Cure by Helen Epstein.

In 10 countries in sub-Saharan Africa, HIV has infected 10 percent or more of adults. No other region of the world has a country with a prevalence rate in the double digits; in North America and Europe, HIV infection has never even reached 1 percent—anywhere. To tease out the reasons for the difference, epidemiologists have journeyed deep into one of sub-Saharan Africa's thickest and dankest jungles: human sexual behavior. AIDS researchers over the past two decades have dissected when Africans start having sex, how many partners they have, how frequently they do it, their marital status and condom use, whether sex involves the exchange of money or a gift, the ability to refuse, exotic ritual practices, and orifice preferences. Uganda has received particularly close scrutiny, and is at the hub of Helen Epstein's new book, The Invisible Cure: AIDS in Africa.

As Epstein recounts, Uganda had one of the world's most intense AIDS epidemics, peaking in 1991 at an adult prevalence rate of 15 percent, though this has since dropped by more than half. Many trees have died for documents that conclude that "we may never fully know" what accounts for this "miracle" and why it has happened in only a few other countries. Epstein sides with the camp that attributes Uganda's HIV/AIDS drop to behavior change. This was catalyzed by an "extraordinarily pragmatic and candid" response to the epidemic at all levels of society—in contrast to many other devastated countries, where health officials misunderstood how HIV was spreading. The main driver of severe HIV/AIDS epidemics is the distinct way that populations form sexual networks, Epstein argues. And on this topic, she hits many high notes. Ultimately, however, Invisible Cure makes a more convincing case for the cause of double-digit HIV/AIDS epidemics than for their cure.

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Epstein, a lapsed laboratory scientist who did graduate work in public health, is a plucky and enterprising character. She abandoned her molecular studies of insects for a self-designed (though ill-fated) AIDS vaccine research project in Uganda and then visited half a dozen sub-Saharan countries over the next decade as a consultant for the Ford Foundation and Human Rights Watch and as a journalist. Her time in Africa convinced her that home-grown social movements powerfully can lead to partner reduction and curb HIV's spread.  Forget "tired stereotypes" about how Africans are more promiscuous and have more premarital sex, or indulge in bizarre customs like "widow cleansing" and "dry sex." Epstein authoritatively cites research that debunks these as the explanations for high rates of HIV/AIDS. She also persuasively questions the once-popular biological argument that pointed to the circulation in Africa of more infectious HIV subtypes. Instead, as Epstein explains, scientists who model the spread of HIV showed as long ago as 1993 the dangers of what they call "concurrency networks."

In many sub-Saharan African locales, both men and women have long-term sexual relationships with a few people at a time. This concurrent partnering contrasts with the serial monogamy that is common in, say, the United States, where people typically move from relationship to relationship or have brief affairs. One provocative study that Epstein cites compared an imaginary population that practiced concurrent partnering with one that was serially monogamous. Each population had the same number of partners over five years. HIV spread 10 times faster in the concurrency network.

"If the network of concurrent relationship serves as a superhighway for HIV, partner reduction would be like a sledgehammer, breaking up the highway into smaller networks," Epstein writes. She celebrates the well-publicized "Love Carefully"/"Zero Grazing" campaigns in Uganda. These vague slogans did not encourage abstinence but instead implicitly recognized concurrent relationships as a cultural norm and encouraged men in particular to avoid "short-term casual encounters." Epstein also praises community-based AIDS groups in Kagera, Tanzania, for similarly encouraging frank talk about the disease and spreading the word that casual sex carries great risks. Epstein repeatedly laments that these approaches have received scant attention.

Reducing the number of partners plainly makes sense as an HIV prevention strategy. However, it's only one of many variables in a maddeningly complex equation. I finished the book with only the fuzziest idea of how the Ugandan and Tanzanian campaigns relate to the mathematical modeling that compared concurrency with serial monogamy. These populations were still practicing concurrency, albeit concurrency lite.

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The bad guys in Epstein's narrative are the misguided, moneyed donors and public-health officials who try to impose their agendas—condom promotion, abstinence, treating other sexually transmitted diseases, microloans—without paying close enough attention to local realities. "As a result, the programs they introduced were largely ineffective and may have inadvertently reinforced the stigma, shame and prejudice surrounding the disease," she writes, ruing their trampling of smaller, more effective projects. Epstein also chides South Africa President Thabo Mbeki for flirting with AIDS denialists, Ugandan President Yoweri Museveni for flirting with George W. Bush's Christian Right agenda, and Swaziland's polygamous King Mswati III for flirting with young Swazi women. As one of my friends says about Vernor's Ginger Ale, it's a busy drink. At times, Invisible Cure ends up reading like a collection of feature stories about AIDS in Africa—several of them told earlier in depth by others, as in Mark Schoof's 1999 Pulitzer Prize-winning Village Voice series.

Epstein could have skipped most of this well-trodden terrain and drilled more deeply into the book's main thesis. By the end of Invisible Cure, much remains mysterious about how to apply the lessons of Uganda and Kagera. How do you create social movements that encourage partner reduction without condemning all concurrency? And we have no idea whether such efforts will have anywhere near the impact she purports. A mix of behavioral and biological forces drives HIV's spread (including one important factor, a pre-existing herpes simplex virus-2 infection, which oddly receives no mention in the book). Several tools now exist to prevent HIV transmission, and, like drugs that treat the infected, they clearly work best in combination. Epstein acknowledges this and calls for more programs that promote partner reduction and educate people about concurrency. Hallelujah. But it's worth keeping in mind that Uganda, despite its miracle, had an adult-prevalence rate of 6.7 percent in 2005, which is still devastatingly high.

This cloud over Uganda's miracle may relate to serious questions that prominent researchers studying Ugandan sexual behavior have raised about the role that behavior change played in the HIV prevalence drop from 1991 to 2005. To begin with, there is a dearth of reliable data from the early years of the epidemic from which to figure out precisely what led to the decline. In addition, one study found that from 1994 to 2003, prevalence fell mainly because of deaths from AIDS and the increasing use of condoms. Rather than critically parsing and addressing these arguments in the main text, Epstein relegates them to endnotes and chides other journalists for their "misleading" stories about the analyses. Another large study  of five African cities with different HIV prevalences did not find that concurrency explained much of anything. It, too, is explained away in an endnote. (Editor's note: This study appeared in the endnotes in the galley of the book sent by the publisher to reviewers. In the book's final edition, the discussion was moved into the main text.)

Another  of five African cities with different HIV prevalences did not find that concurrency explained much of anything. It, too, is explained away in an endnote.

There's a sobering coda to Uganda's success that was reported at last August's international AIDS conference, maybe too late for Epstein's book deadline: It's fragile. A large, multiyear study in the country showed an upswing in prevalence between 2000 and 2005. This resembles the drop and rise seen in many gay communities in the United States and Europe. People become fatigued by prevention campaigns, and, in communities that have access to anti-HIV drugs, there's also decreasing fear of the virus as funerals become less frequent and fewer emaciated people walk the streets. Until there's a safe and effective AIDS vaccine, which is still nowhere in sight, prevalence likely will rollercoaster just about everywhere.

Fortunately, new prevention strategies promise to come on line soon. Well-done trials recently proved that circumcision can reduce the risk of transmission by about 60 percent, and several novel studies now under way are investigating the efficacy of different drugs, microbicides, female diaphragms, and the targeting of people who recently became infected and account for a disproportionate amount of transmissions. Thanks to Epstein and the researchers she celebrates, there's also increasing awareness about the role of concurrent partnerships. But the cure for AIDS epidemics? That remains hard to see, if not wholly invisible.