September 16, 2009
US study shows AH1N1 flu undetected in pigs for a decade
The AH1N1 influenza pandemic was circulating undetected in pigs for at least a decade before it jumped to people, and much better surveillance is needed among both pigs and people, an expert said on Tuesday (Sep 15).
Molecular tests show the swine flu virus made a mutational jump as it passed from pigs to humans, which apparently happened recently, according to Michael Worobey of the University of Arizona.
Worobey, who specializes in tracking viruses using a so-called molecular clock, said the virus most likely has been circulating under the radar in pigs for the better part of 10 years.
AH1N1 flu was first detected in April and declared a pandemic in June. It has spread quickly around the world but so far causes moderate illness, to the relief of public health experts.
Worobey added that influenza viruses mutate regularly and are easy to trace using their rate of change.
