Proceedings of the National Academy of Sciences of the United States of America
A 2007 study by Michael Worobey and Dr. Arthur Pitchenik published in the "Proceedings of the National Academy of Sciences of the United States of America" claimed that, based on the results of genetic analysis, current North American strains of HIV probably moved from Africa to Haiti before entering the United States around 1969, probably through a single immigrant. However, a teenager named Robert Rayford died in St. Louis, Missouri, possibly of complications from AIDS in 1969, having most likely become infected with the virus "before" 1966. This would imply that there were prior carriers of HIV-strains in North America.