Oct. 29, 2007 -- HIV, the virus that causes AIDS, may have arrived in the U.S. a dozen years before AIDS was recognized in 1981.
So say scientists including the University of Arizona's Michael Worobey, PhD.
They analyzed HIV DNA saved in 1982-1983 from five AIDS patients who had recently emigrated from Haiti to Miami. Those five Haitians were among the first recognized AIDS patients.
Using a computer program, Worobey's team traced the lineage of the patients' HIV DNA, based on the assumption that HIV spread to the U.S. via Haiti.
They concluded that HIV arrived in Haiti from Africa in 1966, around the time that many Haitian professionals were returning from working in Africa's newly independent Congo.
Worobey and colleagues also estimate that HIV spread from Haiti to the U.S. in 1969 (or at least between 1966 and 1972).
HIV "was circulating in one of the most medically sophisticated settings in the world for more than a decade before AIDS was recognized," the researchers conclude.
The researchers acknowledge that their calculations could be wrong. Scientists don't know the precise origins of HIV.
They speculate that HIV "may well have been spreading slowly for an extensive period, perhaps in the heterosexual population, before entering the highest risk men-who-have-sex-with-men subpopulation, where it spread explosively enough to finally be noticed."
Their findings appear in this week's early online edition of the Proceedings of the National Academy of Sciences.