New HIV Infections Steadily Declining

In its annual update on the status of the global epidemic, the Joint United Nations Programme on HIV/AIDS (UNAIDS) reported a 17% drop in the number of new HIV infections over the past eight years and suggested that the spread of HIV appears to have peaked in 1996, when 3.5 million new infections occurred.

According to the report, which was released last month in advance of World AIDS Day, an estimated 2.7 million new HIV infections occurred in 2008. This brings the estimated number of people living with HIV to 33.4 million, slightly higher than in 2007 when 33 million were estimated to be living with the virus. This is largely due to the life-prolonging effect of antiretrovirals (ARVs). UNAIDS estimates that there are now about four million people in low- and middle-income countries receiving ARVs—a 10-fold increase over the past five years. AIDS-related mortality peaked in 2004, when there were 2.2 million deaths. Last year, it is estimated that there were two million AIDS-related deaths.

The 2008 data reflect advances in software that have enabled epidemiologists to more reliably estimate HIV incidence using updated mathematical models. The more accurate accounting is expected to help countries more precisely define the scope of the epidemic in high-risk regions and populations. A dozen countries have used a model to analyze HIV incidence by the mode of transmission. This enables epidemiologists to predict where new infections are likely to occur, both generally and within pre-identified subgroups. This approach enabled Uganda to identify an estimated number of new infections that may occur among heterosexual couples considered at low risk of HIV infection.

The latest data also found dramatic variations in HIV prevalence within countries, a sign that prevention strategies need to be tailored to local needs and that national responses to the AIDS epidemic should be decentralized, according to UNAIDS. “The common failure to prioritize focused HIV prevention programs for key populations is especially apparent,” according to the report. “Even though injecting drug users, men who have sex with men, sex workers, prisoners, and mobile workers are at higher risk of HIV infection, the level of resources directed toward focused prevention programs for these groups is typically quite low, even in concentrated epidemics.”

For instance, although serodiscordant couples—in which one partner is HIV infected and the other is not—account for a substantial percentage of new infections in some African countries, HIV testing and counseling programs are seldom geared specifically toward this risk group, the report said. Similarly, many programs that have targeted adolescents fail to grasp some of the key determinants of their vulnerability to HIV. —Regina McEnery