AIDS traced back to single immigrant

November 13, 2007

WILL DUNHAM, The Scotsman

A SINGLE immigrant who carried the AIDS virus from Haiti to the United

States in about 1969 set the stage for it to sweep the world in an

epidemic, experts said yesterday.

Researchers conducted a genetic analysis of stored blood samples from

early AIDS patients. They found that HIV was brought to Haiti by an

infected person from central Africa in about 1966 and then came to the

US around three years later.

The scientists believe 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 US population and then to other

countries. The path the virus travelled as it jumped from nation to

nation has long been debated by scientists.

Worobey, an evolutionary biologist at Arizona University, said

the new study indicates that HIV infections were occurring in the US

for roughly 12 years before AIDS was first recognised by scientists as

a disease in 1981. Many people had died by that point.

AIDS has killed more than 25 million people.

" It is somehow chilling to know it was probably circulating for so

long under our noses, " Mr Worobey said. " That one infection would have

become two, and then it doubles and the two becomes four.

" So you have a period - probably a fair number of years - where you're

dealing with probably fewer than 100 who are infected.

" And then, as with epidemic expansion, at some point 100 becomes 200,

you start getting into thousands, tens of thousands. 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 study was published in the journal Proceedings of the National

Academy of Sciences.

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