Provocative new research shows that treating people with the AIDS virus can provide a powerful bonus: It cuts the risk that they will infect others.
For every 100 people with HIV who started taking AIDS drugs, new infections dropped by 3 percent in the western province where the study was done. The number of new infections there has been cut in half since 1996, matching a rise in treatment.
"The more people you put on therapy, the less transmission there is," said Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases. The drop in new cases in Canada probably "could not be explained by anything else," he said.
The U.S. government helped pay for the study. Results were published online yesterday by the British medical journal Lancet and were being presented at the International AIDS Conference in Vienna.
The results suggest that Canada's policy of free AIDS care is having a double benefit: to the people being treated and to the public's health.
In the United States, the study should boost efforts to more aggressively test and treat people, and to plug funding gaps that keep many from getting care now, AIDS experts said. An estimated 1.1 million Americans have HIV, and about 20 percent of them don't know it. About 55,000 new infections occur each year in the United States, a number that has held steady for a decade.
Finding ways to prevent HIV infection is critical because there is no vaccine or cure for AIDS. Recommended treatment is a combination of medicines that lowers the amount of virus that infected people harbor, often to below detectable levels.
A study a decade ago in Africa found that people with these very low levels of virus were less likely to infect others. Treating pregnant women with HIV lowers the amount of virus they have and the risk they'll pass it on to their babies.
The new study is the first clear evidence that the same principle holds true on a population level, in everyday community settings.
Rates of other sexually spread diseases rose during the study period, suggesting that safer sex behaviors were not responsible for the drop in new HIV infections - treatment was.