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Logo of bmjThis ArticleThe BMJ
BMJ. 2007 November 24; 335(7629): 1069.
PMCID: PMC2094207

WHO and UN slash their estimates of global HIV prevalence

The World Health Organization and the United Nations have revised downwards their estimate of the number of people infected with HIV in 2007—from nearly 40 million to 33.2 million.

“The single biggest reason for the reduction in global HIV prevalence figures in the past year was the recent revision of estimates in India after an intensive reassessment of the epidemic in the country,” says a report by UNAIDS (the joint United Nations programme on HIV and AIDS) and WHO.

About 50% of the difference is due to the reduction in the estimated prevalence in India and another 20% to a revised estimate in several countries in sub-Saharan Africa, including Nigeria, Mozambique, Zimbabwe, Kenya, and Angola.

The revised estimate for India puts the number of people with HIV at 2.5 million, down by more than half from the previous estimate of 5.7 million.

“These improved data present us with a clearer picture of the AIDS epidemic, one that reveals both challenges and opportunities,” said Peter Piot, executive director of UNAIDS. “Unquestionably, we are beginning to see a return on investment: new HIV infections and mortality are declining, and the prevalence of HIV is levelling. But with more than 6800 new infections and over 5700 deaths each day [resulting from] AIDS we must expand our efforts.”

The number of new HIV infections is expected to reach 2.5 million in 2007, including 330 000 children under 15 years old, says the report.

Ron Brookmeyer, professor of biostatistics at the Johns Hopkins Bloomberg School of Public Health, Baltimore, said that more accurate estimates and trends “will ultimately lead to improvements in the design and evaluation of prevention programmes.”

Professor Brookmeyer, who also chaired the independent panel review on epidemiological estimates convened by UNAIDS and WHO, said, however, that there is “a need to further improve the representativeness of the underlying data [and] to expand disease surveillance systems to better track sub-epidemics in risk populations within each country.”

Kevin De Cock, WHO's director for HIV and AIDS, said that the new estimates “are of a better quality than those of the past.” But he added, “We need to continue investing more in all countries and [in] all aspects of strategic information relating to health.”

Overall the outlook is still grim, and some South East Asian countries have reported sharp increases in the number of new HIV infections. Vietnam and Indonesia have registered the fastest increases in incidence in the region—in Vietnam the number of new cases rose from 120 000 in 2000 to 260 000 in 2005.

Sub-Saharan Africa, however, remains the most severely affected region. The report estimates that the number of people newly infected with HIV in Sub-Saharan Africa will reach 1.7 million in 2007. This brings the total number of people in the region with HIV to 22.5 million, 68% of the world total. In 2007 about 1.6 million people in the region died from AIDS, more than two thirds of the global total of 2.1 million.


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