Long March

A quarter-century after the discovery of AIDS, the struggle against it continues.

THE CREDIBILITY of United Nations AIDS statistics took a hit this year when some prevalence estimates turned out to have been exaggerated. In its latest annual report on the pandemic, UNAIDS presents its numbers cautiously, reporting that between 34.1 million and 47.1 million people are living with the HIV virus. But as far as one can tell from imperfect data, the news on AIDS remains awful. Even though the world is spending around $8 billion a year on treatment, prevention, and the care of orphans in poor and middle-income countries, more people are dying from AIDS; more people are being infected; and the number of people living with the virus is at a record level.

The clearest achievement in the battle against the virus has been to boost the number of people being treated to 1.7 million. In sub-Saharan Africa, home to three in five people with HIV, the number receiving antiretroviral medicines has jumped tenfold in three years. The World Health Organization says that an additional 5 million or so people worldwide urgently need treatment, so this is not yet a victory. And even the progress achieved so far is subject to caveats.

The early studies of treatment in poor countries suggested that supplies of medicines could be made reliable and that patients would take them as directed. But successful pilot projects don't always work well on a larger scale: As treatment efforts expand they must face the challenges of dealing with harder-to-serve groups and of enlisting extra medical personnel without diluting quality. Moreover, there's a theoretical danger that the availability of treatment, particularly when coupled with food handouts or other services, might increase risky behavior. True, the offer of treatment may induce people to be tested for HIV, and this can lead to more responsible behavior. But on the other hand it may not -- people who test negative may get the idea that they are somehow immune, while people who test positive may feel there is nothing to lose from casual coupling. This isn't a reason to hold back treatment, particularly since AIDS drugs can make people less infectious. But it's an issue that bears watching.

Beyond the expanding and careful monitoring of treatment programs, the big challenge is to get serious about prevention. Worldwide, 50 percent more people were infected with HIV this year than died for lack of treatment, and the need for constant vigilance is illustrated by Uganda and Thailand, two countries that had succeeded in controlling the virus a few years ago but have started to backslide more recently. The new U.N. report cites some cases in which prevention efforts may have worked: Seven African countries have experienced a decline in HIV prevalence among young urban adults. In Botswana, a country that has received especially generous foreign assistance for its AIDS program, HIV prevalence among pregnant women ages 15 to 19 fell by more than a fifth between 2003 and 2005. But even Botswana illustrates how far there is to go. According to the U.N. report, only about one in three people ages 15 to 24 understands the basics of how HIV is transmitted.