In San Diego Saturday at the annual meeting of the American Association for the Advancement of Science, researchers heard an optimistic assessment of the "test-and-treat" strategy's potential to halt the AIDS epidemic. Aggressive voluntary testing efforts combined with immediate antiretroviral (ARV) treatment of those infected form the basis of the strategy.

In the last five years, access to ARVs has widened in the developing world. However, delayed testing means the drugs are often given too late in the course of infection, by which time the patients already may have transmitted HIV, said Brian Williams of the South African Center for Epidemiological Modeling and Analysis. "The problem is we are using drugs to save lives, we're not using them to prevent infection," Williams said.

An estimated 20 to 25 percent of US residents with HIV do not know they are infected, noted Dr. Kenneth H. Mayer of Brown University. These undiagnosed patients are the source of many HIV transmissions, Williams said.

With early treatment upon diagnosis, plasma viral loads can be cut to one ten-thousandth of previous levels, making that person one twenty-fifth as likely to transmit HIV, Williams said, a reduction in virus that can help break the transmission cycle, he said.

The strategy requires a lifetime commitment to treatment, Mayer said. The director of the National Institute of Allergy and Infectious Disease (NIAID), Dr. Anthony Fauci, recently announced a series of initiatives including studies of test-and-treat in Washington, D.C., and New York City, Mayer said.

"NIAID already is conducting several studies designed to answer the key research questions that underpin the test-and-treat concept," said Carl Dieffenbach, director of the agency's AIDS division. "Through this partnership, NIAID is working with [CDC] to design a study to answer whether implementing a combined strategy of expanding HIV testing, diagnosing infection early, and bringing HIV-infected patients to medical care and treatment is feasible."