DETAILED STUDY ON SPREAD OF H.I.V. IN U.S.

An unusually detailed study of people newly infected with H.I.V. in
the United States has confirmed that the majority of new cases occur
among gay and bisexual men and that blacks are most at risk. But the
data show that whites and blacks tend to be infected at different
times in their lives with the virus that causes AIDS.

Most new infections of white gay and bisexual men occur when the men
are in their 30s and 40s, the study found, while black gay and
bisexual men are more likely to be infected in their teens and 20s.
The results were reported on Thursday by the Centers for Disease
Control and Prevention.

The C.D.C. reported last month that the study found that the virus
was spreading faster in the United States than had been thought. In
2006, the study found, 56,300 people were newly infected with H.I.V.
- -- 40 percent more than the agency's previous estimate of roughly
40,000 new cases a year. The study was performed using new technology
that allowed researchers to distinguish between new and older infections.

Dr. Kevin Fenton of the C.D.C. said the study's findings served "as a
powerful reminder that the U.S. epidemic of H.I.V. disease is far from over."

The details of the agency's demographic analysis were released on
Thursday in the hope that knowledge of the age, race and other
characteristics of the newly infected would better direct prevention efforts.

"The data really confirm what we had suspected and known before,"
said Dr. Fenton, who emphasized the disease's "disproportionate
impact on gay and bisexual men and on blacks and Latinos."

Black people, who make up about 12 percent of the population,
accounted for more than 45 percent of the new infections, the study
found, and the disparity was particularly acute among women.

Black women are nearly 15 times as likely to be infected with H.I.V.
as white women. Hispanic women are four times as likely to be
infected as white women. Black men have six times the H.I.V.
incidence rate of white men and nearly three times that of Hispanic men.

Among those newly infected with the virus, black men were no more
likely to be drug users or to engage in risky sex than were white
men, according to the study. More research is needed to explain why
young black men are at such greater risk for contracting the disease,
but there are several hints from other studies, researchers said.

The fact that proportionally more blacks than whites are already
infected would tend to produce higher transmission rates among
blacks, said Dr. Richard Wolitski, acting director of the center's
division for H.I.V. and AIDS prevention. Young black men are much
more likely to have been incarcerated. Infection rates among former
convicts are high, largely because of behaviors outside of prison,
studies show.

Dr. Wolitski said young black gay and bisexual men also tended to
have partners who were older than their white counterparts and thus
were more likely to have already been infected.

Girls and women make up 27 percent of those newly infected with the
virus, and 80 percent of them contracted H.I.V. because of high-risk
heterosexual contact. Among newly infected males, 81 percent of white
men and 63 percent of black men were gay or bisexual.

In one of the most dismal statistics provided by the centers,
researchers said that 80 percent of gay and bisexual men in 15 cities
had not been reached by intensive H.I.V. prevention efforts that have
proven effective. Agency officials said that more must be done,
including expanded H.I.V. screening programs and better directing of
prevention efforts at those most at risk.