TORONTO - An international team of researchers warns pig populations will need to be closely monitored in future for emerging influenza viruses.
The researchers, from the U.S., Britain and Mexico, made the suggestion in an article on the origins of the new swine flu virus published in the journal Science.
They say the genes that make up the new H1N1 flu virus have been circulating undetected in pigs for an extended period.
But by studying a number of full or partial genetic blueprints of viruses from Mexico and the United States, they confirmed that this particular combination of gene segments has never been previously reported among H1N1 or human flu viruses.
They say all the genes originated in birds, but made their way into pigs at various points in history from 1918 to 1998.
The researchers say the genetic sequences of the genes don't carry signatures of either virulence or high transmissibility found in other flu viruses, so something else must account for the virus's ability to spread easily in people.
