The global prevalence of HIV has fallen to an estimated 33.2 million, according to new data released today by the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO) in their annual AIDS epidemic update. The decline largely reflects changes in the way that HIV prevalence is estimated, UNAIDS says.
Their data also suggest that global HIV incidence has fallen to 2.5 million from a peak of 3 million in the late 1990s, and the number of people dying from AIDS-related illnesses – estimated at 2.1 million – has also declined as a result of the impact of ARV treatment programmes.
“Unquestionably, we are beginning to see a return on investment,” notes UNAIDS Executive Director Dr Peter Piot. “New HIV infections and mortality are declining and the prevalence of HIV levelling. But with more than 6,800 new infections and over 5,700 deaths each day due to AIDS we must expand our efforts in order to significantly reduce the impact of AIDS worldwide.”
New methodologies, revised data
UNAIDS says that the latest figures reflect “improved and expanded epidemiological data and analyses that present a better understanding of the global epidemic.”
UNAIDS, WHO and the Reference Group on Estimates, Modelling and Projections comprehensively reviewed their methodologies and monitoring systems to provide epidemic estimates that reflect improvements in country data collection and analysis, as well as a better understanding of the natural history and distribution of HIV infection.
In addition, new assumptions have also been made as a result of a better understanding of the natural history of untreated HIV infection. Notably, the average number of years that people living with HIV are estimated to survive without treatment has been increased from nine to eleven years. This longer average survival period has resulted in lower estimates of new HIV infections and deaths due to AIDS.
The current estimate of 33.2 million [range, 30.6 – 36.1 million] people living with HIV is more than six million fewer people than the 2006 estimate of 39.5 million [range, 24.5 – 47.1 million] . UNAIDS says that “applying the improved methodology retrospectively to the 2006 data, the 2007 report revises that figure, now estimating that in 2006 there were 32.7 million [range, 30.2 – 35.3 million] people living with HIV.”
The main reason for this reduction in global HIV prevalence was the recent downward revision of estimates in India. This, combined with further revisions of estimates for five sub- Saharan African countries (Angola, Kenya, Mozambique, Nigeria, and Zimbabwe) account for 70% of the reduction in HIV prevalence as compared to 2006 estimates.
Global HIV incidence peaked but HIV prevalence still increasing
Global HIV incidence—the number of new HIV infections per year—is now estimated to have peaked in the late 1990s at over 3 million [2.4 – 5.1 million] new infections per year, and is estimated in 2007 to be 2.5 million [1.8 – 4.1 million] new infections, an average of more than 6,800 new infections each day.
However, although the global prevalence of HIV infection appears to have levelled off based on the new estimates, the total number of people living with HIV is still increasing due to new HIV infections, combined with longer survival times.
Sub-saharan Africa remains the global region most affected by HIV and AIDS. UNAIDS notes that “AIDS-related illness is among the leading causes of death globally and remains the primary cause of death in Africa.” In addition, the report highlights that more than two-thirds (68%) of all people with HIV live in sub-Saharan Africa, where more than three quarters (76%) of all AIDS-related deaths in 2007 occurred.
UNAIDS and WHO officials point out that the new estimates do not change the need for immediate action and increased funding to scale up towards universal access to HIV prevention, treatment, care and support services.
UNAIDS. AIDS epidemic update: December 2007. and associated press releases and other reports, available from the UNAIDS website.