How was the Aids situation in Africa so greatly overstated?

UN estimates of the extent and location of the Aids virus are now being shown to have given an inaccurate picture of the epidemic…

UN estimates of the extent and location of the Aids virus are now being shown to have given an inaccurate picture of the epidemic

Researchers said nearly two decades ago that Rwanda was part of an Aids Belt stretching across the midsection of Africa, a place so infected with a new, incurable disease that, in the hardest-hit places, one in three working-age adults were already doomed to die of it.

But Aids deaths on the predicted scale never arrived here, government health officials say. A new national study illustrates why: The rate of HIV infection among Rwandans ages 15 to 49 is 3 per cent, according to the study, enough to qualify as a major health problem but not nearly the national catastrophe once predicted.

The new data suggest the rate never reached the 30 per cent estimated by some early researchers, nor the nearly 13 per cent given by the United Nations in 1998.


The study and similar ones in 15 other countries have shed new light on the disease across Africa. Relying on the latest measurement tools, they portray an epidemic that is more female and more urban than previously believed, one that has begun to ebb in much of East Africa and has failed to take off as predicted in most of West Africa.

Yet the disease is devastating southern Africa, according to the data. It is in that region alone - in countries including South Africa, Botswana, Swaziland and Zimbabwe - that an Aids Belt exists, the researchers say.

"What we know now more than ever is southern Africa is the absolute epicentre," said David Wilson, a senior Aids analyst for the World Bank, speaking from Washington.

In the West African country of Ghana, for example, the overall infection rate for people ages 15 to 49 is 2.2 per cent. But in Botswana, the national infection rate among the same age group is 34.9 per cent. And in the city of Francistown, 45 per cent of men and 69 per cent of women ages 30 to 34 are infected with HIV, the virus that causes Aids.

Most of the studies were conducted by ORC Macro, a research corporation based in Maryland, and were funded by the US Agency for International Development, other international donors and various national governments in the countries where the studies took place.

Taken together, they raise questions about monitoring by the UN Aids agency, which for years overestimated the extent of HIV/Aids in East and West Africa and, by a smaller margin, in southern Africa, according to independent researchers and UN officials.

"What we had before, we cannot trust it," said Agnes Binagwaho, a senior Rwandan health official.

Years of HIV overestimates, researchers say, flowed from the long-held assumption that the extent of infection among pregnant women who attended prenatal clinics provided a rough proxy for the rate among all working-age adults in a country. Working age was usually defined as 15 to 49. These rates also were among the only nationwide data available for many years, especially in Africa, where health tracking was generally rudimentary.

The new studies show, however, these earlier estimates were skewed in favour of young, sexually active women in the urban areas that had prenatal clinics. Researchers now know that the HIV rate among these women tends to be higher than among the general population.

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 UN 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 per cent, significantly lower than the UN rate of 21.5 per cent. In Burundi, which borders Rwanda in central East Africa, a national study found a rate of 5.4 per cent, not the 8.3 per cent 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 per cent - compared with an estimated UN rate of 7 per cent.

Such disparities, independent researchers say, skewed years of policy judgments and decisions on where to spend precious healthcare 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 UN 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 per cent in a 2002 report to 7.2 per cent 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 realise that indeed we have overestimated the epidemic a bit," he said.