Researchers claim discovery of HIV source

Researchers say they have traced the predominant strain of the AIDS virus in the United States and Europe to the Caribbean country of Haiti.

They believe their research provides conclusive proof that the strain was brought into the US in the late 1960s.

HIV-One group M sub-type B, is the strain of HIV which predominates in the United States, Europe, large parts of South America, Australia and Japan.

Scientists say they now know where it came from. They examined archived blood samples from five early AIDS patients and analysed genetic sequences from another 117 AIDS patients from around the world.

With this data they recreated a family tree for the virus, which they believe shows conclusively that the strain came to the United States via Haiti in around 1969.

The scientists say that once the virus was in the US, it moved explosively around the world.