An international team of scientists have discovered the origins of the strain of HIV common to the continents of US, Australia, South America, Australia as well as Japan.
According to the scientists whose report is detailed in the Proceedings of the US National Academy of Sciences, this strain can be traced to the country of Haiti.
The HIV-1 group M subtype B strain passed from Haiti to the US in around 1969 before spreading further, write the team.
The team came to their conclusions after examining stored and classified blood samples from five early AIDS patients. They were all Haitian immigrants to the United States. The team also examined genetic sequences from another 117 Aids patients from around the world.
Using this data, the scientists created a family tree for the virus. From this they were able to pinpoint conclusively that the strain came to the US via Haiti - probably via a single person - in around 1969.
According to Michael Worobey of the University of Arizona in Tucson, one of the study's authors, HIV first arrived in Haiti in the mid-1960s. It was probably from Africa where HIV is thought to have originated.
"By 1966 the virus first starts spreading in Haiti. A few years later one variant from Haiti gives rise to what would then light the fuse and explode around the world as the Aids pandemic that we first became aware of ", says Worobey.
Prof Worobey and his team are not done yet. They now want to trace the strain back further. They suspect that the strain probably arrived in Haiti from the Congo via Haitians who worked in Africa during those years.
Why dig up the past? Because says Worobey, understanding the origins of this and other strains of HIV will help scientists predict better how the virus might mutate in the future.