AIDS has become the worst pandemic in human history, eclipsing even the Black Death of the 14th century. Unlike the plague, AIDS often kills the descendants of victims who have passed on. There is no excuse for the failure to tackle this scourge; there is ample evidence of effective ways to respond to the disease, to treat and even prevent it. All that is lacking is the political will to do so. Concerned governments must seize the moment: The 15th International AIDS Conference, which opened this week in Bangkok, is an opportunity to reaffirm the global commitment to fighting AIDS.

The numbers are shocking. According to a new study by UNAIDS, the Joint U.N. Program on HIV/AIDS, 38 million people worldwide have contracted the deadly disease, 5 million in the past year alone, the largest increase ever recorded. More than 20 million people have died of AIDS over the past two decades; 3 million lost their lives last year, 500,000 of them children. An estimated 15 million children under age 18 worldwide have lost one or both parents to AIDS.

The economic costs of AIDS are equally numbing. The disease tends to hit middle-age adults hardest, effectively depriving nations of their most productive workers. In the hardest-hit countries of Africa, death rates among 20- to 40-year-olds have tripled. It is estimated that AIDS can represent a tax of nearly 4 to 12 percent on labor costs, particularly in the form of skyrocketing health care costs. The effects are transmitted across generations, not only in the form of infections, but in the diversion of resources from infrastructure development to health and social welfare programs.