How AIDS in Africa Was Overstated

The new studies rely on random testing conducted across entire countries, rather than just among pregnant women, and they generally require two forms of blood testing to guard against the numerous false positive results that inflated early estimates of the disease. These studies also are far more effective at measuring the often dramatic variations in infection rates between rural and urban people and between men and women.

UNAIDS, the agency headed since its creation in 1995 by Peter Piot, a Belgian physician, produced its first global snapshot of the disease in 1998. Each year since, the United Nations has issued increasingly dire assessments: UNAIDS estimated that 36 million people around the world were infected in 2000, including 25 million in Africa. In 2002, the numbers were 42 million globally, with 29 million in Africa.

But by 2002, disparities were already emerging. A national study in the southern African country of Zambia, for example, found a rate of 15.6 percent, significantly lower than the U.N. rate of 21.5 percent. In Burundi, which borders Rwanda in central East Africa, a national study found a rate of 5.4 percent, not the 8.3 percent estimated by UNAIDS.

In West Africa, Sierra Leone, just then emerging from a devastating civil war, was found to have a national prevalence rate of less than 1 percent -- compared with an estimated U.N. rate of 7 percent.

Such disparities, independent researchers say, skewed years of policy judgments and decisions on where to spend precious health-care dollars.

"From a research point of view, they've done a pathetic job," said Paul Bennell, a British economist whose studies of the impact of AIDS on African school systems have shown mortality far below what UNAIDS had predicted. "They were not predisposed, let's put it that way, to weigh the counterevidence. They were looking to generate big bucks."

The United Nations started to revise its estimates in light of the new studies in its 2004 report, reducing the number of infections in Africa by 4.4 million, back to the total four years earlier of 25 million. It also gradually decreased the overall infection rate for working-age adults in sub-Saharan Africa, from 9 percent in a 2002 report to 7.2 percent in its latest report, released in November.

Peter Ghys, an epidemiologist who has worked for UNAIDS since 1999, acknowledged in an interview from his office in Geneva that HIV projections several years ago were too high because they relied on data from prenatal clinics.

But Ghys said the agency made the best estimates possible with the information available. As better data emerged, such as the new wave of national population studies, it has made revisions where necessary, he said.

"What has happened is we have come to realize that indeed we have overestimated the epidemic a bit," he said.

On its Web site, UNAIDS describes itself as "the chief advocate for worldwide action against AIDS." And many researchers say the United Nations' reliance on rigorous science waned after it created the separate AIDS agency in 1995 -- the first time the world body had taken this approach to tackle a single disease.

In the place of previous estimates provided by the World Health Organization, outside researchers say, the AIDS agency produced reports that increasingly were subject to political calculations, with the emphasis on raising awareness and money.