The HIV virus arrived the United States in 1969 from Haiti, carried most likely by a single infected immigrant who set the stage for a world epidemic, scientists said on Monday.

According to Reuters, Michael Worobey, a University of Arizona evolutionary biologist, said the 1969 U.S. entry date is earlier than some experts had believed.

The timeline laid out in the study led by Worobey indicates that HIV infections were occurring in the United States for roughly 12 years before AIDS was first recognised by scientists as a disease in 1981.

Many people had died by that point.

“It is somehow chilling to know it was probably circulating for so long under our noses,” Worobey said in a telephone interview, according to Reuters.

The researchers conducted a genetic analysis of stored blood samples from early AIDS patients to determine when the HIV virus first entered the US.


The researchers think an unknown single infected Haitian immigrant arrived in a large city like Miami or New York, and the virus circulated for years, first in the U.S. population and then to other nations.

It can take several years after infection for a person to develop AIDS.

“That one infection would have become two, and then it doubles again and the two becomes four,” Worobey said.

“So you have a period, probably a fair number of years, where you’re dealing with probably fewer than a hundred people who are infected.


“And then quite rapidly you can be up into the hundreds of thousands of infections that were probably already there before AIDS was recognised in the early 1980s.”


The path the virus travelled as it jumped from nation to nation has long been debated by scientists.

The University of Miami’s Dr. Arthur Pitchenik, a co-author of the study, had seen Haitian immigrants in Miami as early as 1979 with a mystery illness that turned out to be AIDS. He knew the government had stored some of their blood samples.


This genetic analysis allowed the scientists to calculate when HIV arrived first in Haiti from Africa and then in the United States.

The researchers have virtually ruled out the possibility that HIV had come directly to the United States from Africa, setting a 99.8 per cent probability that Haiti was the steppingstone.

“I think that it gives us more clear insight into the history of it (the AIDS epidemic) and what path the virus took — and hard objective evidence, not just armchair thinking,” Pitchenik told Reuters.



The number of people with HIV has risen in every region of the world in the past two years, with the fastest increases being seen in East Asia and Eastern Europe and Central Asia.