An analysis of 25-year-old blood samples pushes the arrival of HIV in the United States back to about 1969, 12 years before AIDS was first described by a doctor in Los Angeles. The virus came from Haiti, which served as a Western Hemisphere toehold for the early stages of the epidemic starting in the mid-1960s, according to the analysis.
"There have been some suggestions that the virus may have been [in the United States] before the mid-1970s," says Michael Worobey, a microbiologist at the University of Arizona in Tucson, who led the study. "But there's also been lots of skepticism." He says that his research provides the first "rigorous" evidence of an earlier U.S. arrival of HIV.
"I'm convinced," says Beatrice Hahn, a microbiologist at the University of Alabama School of Medicine in Birmingham. "It's a very nice piece of work that accounts for all the variables."