New data, released by the Centers for Disease Control and Prevention, reflect the success of new treatments and drugs that allow HIV-infected people to survive longer. The numbers also highlight how much the epidemic has changed over the last 2 decades.

AIDS, which was originally predominant among gay white men, is now most prevalent among gay and bisexual black men. African Americans, who make up 13% of the U.S. population, account for 47% of people living with AIDS, followed by whites with 34% and Hispanics with 17%.

Three-quarters of those infected are men, but AIDS is the leading cause of death for African American women between 25 and 34.

At the National HIV Prevention Conference in Atlanta last week, CDC official Ronald Valdiserri called for efforts to address those at greatest risk. "Our challenge today is to build upon successes to date and adapt prevention programs to the unique needs of the sub-populations now affected," Mr. Valdiserri said. "One population in urgent need is gay and bi-sexual men."

One study released at the meeting revealed an extremely high infection rate among men having sex with men, or MSM, consistent with earlier research. Mr. Valdiserri noted that "46% of African American men in the study population [are] infected. This rate was more than twice the rate of white MSM enrolled in the study at 21%, and among Hispanic msm at 17%."

Mr. Valdiserri said that study also documented an alarming number of undiagnosed HIV cases. "Among HIV-infected MSM, 67% of the black men, 48% of the Hispanic men, and 18% of the white men were unaware of their infection before study participation," he said, adding that the figures underscore "the need to reach MSM of all races with testing and prevention services." The data also indicated that HIV cases among MSM increase dramatically with age. Mr. Valdiserri said, "these findings point to the critical ongoing need to reach young MSM with prevention efforts."

New Jersey has had considerable success doing that, with a rapid HIV testing program, in which the client gets results in minutes. Sindy Paul of the New Jersey Department of Health and Senior Services says a high profile media campaign combined with a growing number of rapid test sites is getting results.

"The public has responded to it. Our counseling and testing staff has responded to it. And all the data that we have shows that it has been very important for us," she said. "It has allowed us entry into places we could never be before. For example we now have rapid HIV testing in 11 [hospital] emergency [room] departments. This is so that we can provide access to counseling and testing to high-risk persons who cannot access the health care system in any other way."

The rate of new HIV infections in the United States has remained stable at about 40,000 cases a year since the 1990s. The CDC had hoped to cut that number in half by this year, a goal it has failed to achieve? in part because HIV infected people - diagnosed or undiagnosed - may still engage in high-risk sex. CDC official Ronald Valdiserri says overcoming these obstacles won't be easy.

"And it will not happen overnight," he said. "Our future successes will depend on sustained government and community mobilization against this disease supported by sound scientifically grounded prevention strategies and a continued commitment to both HIV prevention and care."

The CDC budget for HIV prevention is $663 million, two-thirds of which is directed to state and local health departments. Studies like those released at the meeting in Atlanta last week help direct testing, prevention and treatment money to where it is most needed.