The U.S. has significantly underreported the number of new HIV infections occurring nationally each year, with a study released Saturday showing that the annual infection rate is 40 percent higher than previously estimated.
The study, conducted by the Centers for Disease Control and Prevention, found that 56,300 people became newly infected with HIV in 2006, compared with the 40,000 figure the agency has cited as the recent annual incidence.
The findings confirm that HIV, the virus that causes AIDS, has its greatest effect among gay and bisexual men of all races (53 percent of all new infections) and among African Americans.
The new figures are likely to strongly influence a number of decisions about efforts to control the epidemic, said the disease centers' director, Dr. Julie Gerberding, and other experts. Timely data about trends in HIV transmission, they said, is essential for planning and evaluating prevention efforts and the money spent on them.
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“CDC's new incidence estimates reveal that the HIV epidemic is and has been worse than previously known,” Kevin Fenton, who directs HIV prevention efforts at the agency, said Saturday.
A separate historical trend analysis published as part of the study suggests that the number of new infections was probably never as low as the earlier estimate of 40,000 and that it has been roughly stable overall since the late 1990s.
CDC officials said the revised figure did not necessarily represent an actual increase in the number of new infections but reflected the ability of a new testing method to more precisely measure HIV incidence and secure a better understanding of the epidemic.
A paper on the study will be published Wednesday in The Journal of the American Medical Association. The journal and the CDC had planned to release it at a news conference today at the opening of the 17th International AIDS Conference in Mexico City. But the paper was released Saturday because the embargo was broken.
Dr. Philip Alcabes, an epidemiologist at Hunter College in New York, raised questions about the validity of the findings. If they are true, Alcabes said in a statement, the agency has undercounted new HIV infections by about 15,000 per year for about 15 years.
“Therefore, there are roughly 225,000 more people living with HIV in the U.S. than previously suspected,” he said. “The previous estimate was 1 million to 1.1 million.”
The CDC, the federal agency responsible for tracking the AIDS epidemic in the U.S., said its new monitoring system provided more precise estimates than were previously possible of new infections in specific populations. Infection rates among blacks were found to be seven times as high as for whites (83.7 per 100,000 people versus 11.5 per 100,000) and almost three times as high as for Hispanics (29.3 per 100,000 people), a group that was also disproportionately affected.
One-fourth of infected people do not know they are infected because they have not been tested.
The CDC has introduced new prevention efforts including expanding education to people living with HIV, increasing testing and expanding the use of condoms and other programs for high risk populations.
The CDC has known of the new figures since last October when the authors completed a manuscript and sent it to the first of three journals. But the agency refused to release the findings until they were published in a peer-reviewed medical journal.