Proof Positive

How African Science Has Demonstrated That HIV Causes AIDS

When almost all of the samples came back HIV-positive, Carswell organized an expedition to Rakai, consisting of himself, Serwadda, Bayley, Sewankambo, Mugerwa, and a taciturn virologist named Robert Downing. At Masaka Hospital and homes in Rakai villages, the team examined more than 100 patients. They diagnosed 29 people as having Slim and sent their blood to England for HIV testing.

Every one of those 29 patients tested positive.

"I was scared for my country," recalls Serwadda. To learn the true scope of the epidemic and how to control it, Serwadda, Sewankambo, and Mugerwa drafted a research proposal. "These were Ugandans who wrote the proposal, not foreigners who said, 'Do A, B, and C,' " recalls Sewankambo. "I'm proud of that."

Maria Wawer, a public-health researcher from Columbia University, later agreed to collaborate with the Ugandans and help secure American funding. The result was the well-known Rakai Project, which is still producing important research. Separately, the Uganda Virus Research Institute and the British Medical Research Council launched another research project in Masaka, which has produced almost 100 scientific articles.

In their letter to Mbeki, Geshekter and Rasnick asked, "What evidence is there that people with antibodies to HIV live shorter, poorer lives than people in the same community who do not have antibodies to HIV? We know of no such evidence." In fact, each of these Ugandan research projects has conducted exactly the acid test Geshekter and Rasnick asked for, by looking at HIV-positive people living side by side with those who are HIV-negative. If poverty were the real cause of AIDS, then there should be little difference between the fates of the infected and the uninfected.

But the studies found that HIV-infected people died at a rate more than nine times higher than uninfected people. And the Masaka study found that infected people died a full two decades younger, at a mean age of just 34.

Even more compelling evidence that HIV is lethal emerged out of a tragic lapse in Kinshasa, capital of the Democratic Republic of the Congo, then called Zaire.

When the HIV antibody test became available, Kinshasa's sprawling and impoverished main hospital lacked stores of screened blood and staff to run the tests 24 hours a day. During this window period, children came to the hospital in critical need of a blood transfusion, usually because of malaria. With the child facing death, doctors would transfuse unscreened blood, saving samples from the child and the donor for later testing.

In this way, the famous research team Project SIDA, named for the French acronym for AIDS, identified 90 originally uninfected children who were given HIV-infected blood. Among children who survived the illness for which they were given the transfusion, those who received HIV-infected blood suffered a death rate 16 times higher than controls.

"Let me take you back," says Sewankambo. In the beginning, the high proportion of Ugandans with HIV puzzled him. "My thinking was very much affected by the North: This is a gay disease. But if there wasn't that much homosexuality in our community, and we knew there wasn't any, really, then what was the mode of transmission? I was expecting mosquitoes."

The mosquito hypothesis was easy to test. Sewankambo and others examined households in which at least one person had AIDS, testing everyone, including children and grandparents. If AIDS was spread by mosquitoes, the virus should be present almost randomly, and certainly it should be in many children, who are the most susceptible to malaria.

Nothing of the sort was found. Of the sexual partners of the AIDS patients, a striking 71 percent were infected. Yet of the other people living in the household, with whom the patients were not having sex, only two out of 100 of were infected—a woman who was sexually active and her two-year-old son. "It did certainly suggest strongly that it was sexually transmitted," says Sewankambo.

Yet in their letter to Mbeki, Geshekter and Rasnick insisted that the sexual spread of HIV is "merely a very popular assumption," and pointed to a study conducted among couples in California showing that the odds of a man transmitting HIV to a woman during a single act of intercourse are slightly less than one in a thousand. From such first-world studies, they concluded that HIV is not frequently transmitted among heterosexuals anywhere.

"Outrageous," says the lead author of that study, Nancy Padian, who is also conducting research in Zimbabwe. "It's more likely that the epidemiology of a disease would differ in different locations than be the same—just look at cancer and heart disease."

As for African research, it leaves no doubt that HIV is spread heterosexually. The sex and age distribution of HIV on the continent mirror patterns seen with other STDs. Risk factors for having HIV include more sexual partners, being a prostitute, having had sex with a prostitute, and a history of STDs. In Uganda, two studies stand out. In one, wives were more than 100 times more likely to contract HIV if their husband had the virus than if he didn't. The other study, coauthored by Serwadda and Sewankambo, looked at couples in which one partner had HIV and the other didn't. What they found was shockingly simple: The higher the level of HIV in the infected partner, the greater the chance of transmitting it. This study suggests that if a vaccine could merely reduce the amount of HIV in the bodies of infected people, the epidemic could be curtailed. Clearly, this has tremendous implications for the whole world—and it came from research in Africa.

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