A new report by the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO) estimates that the global prevalence of HIV, the proportion of the world’s population infected with the virus that can lead to AIDS, has levelled off.

However, the total number of people living with HIV continues to increase because the world’s population is increasing and people with HIV are living longer. The report estimates 33.2 million people worldwide are living with HIV in 2007.

Improved epidemiological data and estimating methods have improved analysts’ understanding of the global HIV situation, leading to substantial revisions in estimates compared to previous figures, said a statement issued on the WHO website earlier today, 20th November. Last year the total number of people living with HIV was estimated to be 39.5 million.

The new figures mostly reflect the revision of estimates in India after what has been described as “an intensive reassessment of the epidemic in that country”. Together with reassessments of estimates for the five sub-Saharan African countries of Angola, Kenya, Mozambique, Nigeria, and Zimbabwe, the revised figures for India account for 70 per cent of the reduction in estimated HIV prevalence from 2006 to 2007.

UNAIDS Executive Director Dr Peter Piot said:

“These improved data present us with a clearer picture of the AIDS epidemic, one that reveals both challenges and opportunities.”

“Unquestionably, we are beginning to see a return on investment; 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,” he added.

The global incidence rate of HIV, that is the number of people newly infected every year, is now estimated to have peaked toward the end of the 1990s at over 3 million. The estimate for 2007 is 2.5 million, which, as Piot pointed out, represents more than 6,800 new infections a day.

Experts suggest this reflects not only the result of HIV prevention campaigns, but the natural course of epidemics.

The number of people dying from AIDS and related illnesses has also gone down in the last two years, partly because antiretroviral therapy improves survival. However, globally, AIDS remains one of the leading causes of death, and in Africa it is still the number 1 killer. 2.1 million people will have died of AIDS in 2007, suggests the report.

Within Africa, there were an estimated 1.7 million new HIV infections in the sub-Saharan region in 2007, which is significantly lower than the 2001 estimate. However, the region is still severely affected and is home to an estimated 22.5 million people infected with HIV, representing 68 per cent of the total global number. Nearly one third of the world’s total HIV infections and AIDS related deaths occur in eight countries in sub-Saharan Africa.

In Eastern Europe and Central Asia, the number of people living with HIV has increased by over 150 per cent since 2001, from 630 thousand to 1.6 million in 2007.

UNAIDS and WHO explained in their joint statement that the estimates in the new report reflect improvements in the way data from each country is collected and analysed, as well as a better understanding of how HIV develops and spreads. They said “This information is vital in helping countries understand their epidemics and respond to them more effectively.”

Data collection and analysis methods have improved most significantly in sub-Saharan Africa and Asia, and 30 countries in other African regions have carried out population based household surveys, which have helped to improve estimates for countries with similar epidemics but no household survey data to go on.

WHO’s HIV/AIDS Director Dr Kevin De Cock said that reliable data was essential to providing an effective response to the HIV/AIDS epidemic but that:

“While these new estimates are of better quality than those of the past, we need to continue investing more in all countries and all aspects of strategic information relating to health.”

While praising the improved quality of the epidemiological data used by UNAIDS and WHO, Ron Brookmeyer, Professor of Biostatistics and Chair of the Master of Public Health Program, The Johns Hopkins Bloomberg School of Public Health, said there was still further to go:

“Nevertheless, there is a need to further improve the representativeness of the underlying data. There is a need to expand disease surveillance systems to better track the sub-epidemics in risk populations within each country.”

UNAIDS and WHO representatives stressed that while the figures appear to be improving, there was still an urgent need for action and funds to ensure every single human being in the world had access to HIV prevention, treatment, care and support.

Click here for full report “2007 AIDS Epidemic Update” (UNAIDS, PDF document).

Written by: Catharine Paddock