For the next few days, those who care about the epidemic of HIV/AIDS will be focused on the 15th International AIDS Conference, which begins Sunday in Bangkok, Thailand.

The global implications of this disease with no cure are overwhelming: Five million new cases last year alone. One in six South Africans infected. Sharp increases in China, Indonesia, Vietnam and Eastern Europe.

The situation overseas is so dire that it is easy to forget the stubbornness of the disease back home. AIDS is now the leading cause of death for black women ages 25 to 34 — not in some Third World country, but right here in the United States.

Two decades into this plague, and we still don’t really know how to stop it. So you can’t blame the Centers for Disease Control and Prevention for refining its strategy as it seeks to direct precious (and ever-scarcer) federal funds most effectively.

One recent move has been away from general prevention and toward targeting those already infected. But that new strategy, unveiled last year and taking effect now, runs the risk of looking only at where the epidemic is, not where it’s going.

“There are 299 million of you who don’t have HIV, and one million of us who do,” says Kevin Conare, executive director of Action AIDS Philadelphia. “So it makes sense to work with us.” But he and others are concerned that if the “prevention with positives” approach gets too much attention, “we’ll get at the branches and leaves, and not at the root issues.”

Unlike some other public-health decisions made by this administration, this CDC shift in priorities is based on valid research — a study that found that HIV-positive people were rarely receiving any message to watch their sexual behavior. The change in strategy also reflects a change in the social history of the disease. Until recently, “positive people” didn’t live long. Now, thanks to the availability of retroviral drug therapy, more people are living with AIDS than ever.

“We weren’t bringing up safe sex because we weren’t used to people being healthy and living,” says Marla Gold, dean of the Drexel University School of Public Health. “If prevention among those who are infected really works, we’ll see a decrease in the numbers infected. However, you want to know that it works.”

And that’s one outstanding question. The other is: What about trying to prevent the spread of HIV/AIDS among people known to be at risk? The disease is growing most rapidly among heterosexual African American women, yet many agencies working with those women lost CDC funding this year.

For instance, for the last four years, Philadelphia’s Maternity Care Coalition, in collaboration with the Women’s Christian Alliance, has targeted high-risk black women with AIDS education and prevention programs. Last year, it served 1,500 people; this year, due to CDC and city funding cuts, the number will be zero.

“Those of us doing this work are really frightened by what we’re going to see in three to five years,” says Bette Begleiter, deputy executive director of the Maternity Care Coalition. “Why aren’t we going in before people get sick?”

Similar questions are being asked from Washington to San Francisco, and the saddest part is that the amount of money in play is painfully small: Only $49 million in this latest round of grants, spread across the country, even as the disease appears to be on the rise again.

“The real tragedy is that there are scarce resources for prevention,” David Metzger, director of HIV prevention at Penn’s Center for AIDS research, told me as he was preparing to leave for Bangkok. “When you prevent something, there’s no event. Nothing happens. So it doesn’t receive attention or appreciation, not like vaccine development or treatment.”

What a shame that the richest nation in the world should be faced with the heartbreaking choice between helping those at risk of getting a deadly disease and those already infected. Both of these approaches are necessary. Aren’t we big and compassionate enough to do more than one?

Jane R. Eisner is a columnist for the Philadelphia Inquirer. Her e-mail address is jeisner@phillynews.com.