AIDS numbers in U.S. higher than previously thought

The study also showed that prevention efforts are paying off.

Washington Post

WASHINGTON — New federal estimates of the annual number of new HIV infections in the United States, released Saturday, reveal that although the AIDS epidemic here is worse than previously thought, prevention efforts appear to be having some effect.

Even though the number of Americans living with HIV has risen by more than a quarter million people since 1998 — thanks largely to life-extending antiretroviral drugs — the number of new cases each year has declined slightly over that period. That suggests that an infected person’s likelihood of transmitting the virus to someone else is substantially lower now than it was a decade ago.

The new — if indirect — evidence that prevention programs are paying off was one of the few encouraging findings in an update on the American AIDS epidemic issued by the Centers for Disease Control and Prevention on the eve of the 17th International AIDS Conference, which opens today in Mexico City.

“Over 95 percent of people living with HIV are not transmitting to someone else in a given year,” said David Holtgrave, an expert on AIDS prevention at the Bloomberg School of Public Health at Johns Hopkins University. “What that says is the transmission rate has been kept very low by prevention efforts.”

Those include targeting public health messages to high-risk groups, promoting widespread AIDS testing, and getting newly diagnosed people into medical care quickly, which in most cases lowers their infectiousness.

The CDC spends about $750 million a year on AIDS prevention. The main new finding of its report is that HIV incidence in 2006 — the latest year for which data are available — was 56,300 new cases of infection. That is 40 percent higher than the previous government estimate of was 40,000 new cases a year, but statistical back-calculation suggests that HIV incidence has been unchanged since about 2000.

The more accurate estimate was possible for two reasons. A new testing method lets researchers detect infections less than six months old, more quickly than before. New federal regulations are also pushing states to collect data on new HIV infections and not just new AIDS diagnoses.

By the time AIDS is diagnosed, the infection has heavily damaged a person’s immune system, making them vulnerable to unusual infections and cancers. This generally occurs eight to 11 years after a person is infected, assuming no treatment with antiretroviral drugs, which can prolong life for many more years.

In December, The Washington Post reported that CDC was revising HIV incidence upward to between 50,000 and 60,000 cases a year. Saturday’s announcement — and the publication of a paper in this week’s Journal of the American Medical Association — is the first official acknowledgement of the new, higher estimate.