UNAIDS Report Shows HIV/AIDS Stabilizing at High Levels
New Methodology Leads to Significant Revisions in India and Elsewhere
March 2008—The number of people living with HIV worldwide remains extraordinarily high—33.2 million in 2007, including 4.9 million in Asia—but the epidemic appears to have leveled off at a lower point than researchers had previously estimated, according to a report published in December 2007 by UNAIDS.
The 2007 figure is 16 percent lower than the previous year's estimate of 39.5 million. The UNAIDS report explains that this downward turn does not signal a sudden shift in the course of the pandemic but, rather, a more sophisticated methodology used in the collection and interpretation of HIV data, particularly in India. According to the report, 2.5 million people were newly infected with HIV in 2007, including 444,000 in Asia, and 2.1 million died of AIDS-related causes, among them 300,000 in Asia.
The most dramatic piece of news in the UNAIDS report is that global HIV incidence—the number of new infections per year—reached its peak in the late 1990s at more than 3 million. Nonetheless, global prevalence—the overall percentage of adults living with HIV—has remained roughly constant since 2001.
"Unquestionably, we are beginning to see a return on investment—new HIV infections and mortality are declining and the prevalence of HIV leveling," said Dr. Peter Piot, executive director of UNAIDS. "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."
The Asian Picture
In India, a recent national household survey of more than 100,000 people and a tenfold increase in the number of sites participating in HIV surveillance provided more accurate data that led to an adjusted national estimate of 2.5 million people, less than half the 2006 estimate of 5.7 million.
Other severely affected Asian countries have seen drops in their rates of HIV infection, not as a result of statistical revisions but because of successful prevention efforts. Cambodia, Malaysia, Myanmar, and Thailand have registered declines, most notably Cambodia, where prevalence has decreased from 2 percent in 1998 to 0.9 percent in 2007.
In contrast, Indonesia is now home to Asia's fastest-growing HIV epidemic, largely as a consequence of widespread injection drug use. The number of cases in Viet Nam more than doubled between 2000 and 2005. And in China, the number of people with HIV rose by 50,000 to 700,000 in 2007.
The UNAIDS report describes several important methodological changes that produced the new, lower global estimates. First, more countries have implemented national population-based surveys, which provide more accurate assessments than data extrapolated from surveillance in prenatal clinics, which have often been used to determine prevalence. In addition, new mathematical assumptions have led to a downward revision of prevalence in countries that are still using prenatal clinic data rather than national surveys. Finally, the estimated net median survival time for people living with HIV who do not receive treatment was raised to 11 years from nine years, resulting in lower estimates of HIV incidence and AIDS deaths.