H1N1 flu present for years in pigs

(ChinaPost.com.tw) – The new H1N1 virus, which has caused the first pandemic of the 21st century, appears to have been circulating undetected among pigs for years, researchers reported on Thursday.

Although health officials have been watching for new influenza viruses in humans, animal health regulators have missed the opportunity to check swine, the researchers reported.

Britons Andrew Rambaut of the University of Edinburgh and Oliver Pybus of Oxford University, and Yi Guan of the University of Hong Kong examined the genetic sequence of the new H1N1 swine flu virus.

Like others who have done the same, they show it is a mixture of other viruses that had been circulating in pigs, one of which was itself a mixture including swine, human and avian-like genetic sequences.

“We show that it was derived from several viruses circulating in swine, and that the initial transmission to humans occurred several months before recognition of the outbreak,” they wrote.

“Movement of live pigs between Eurasia and North America seems to have facilitated the mixing of diverse swine influenza viruses, leading to the multiple reassortment events associated with the genesis of the (new H1N1) strain,” they added.

“Yet despite widespread influenza surveillance in humans, the lack of systematic swine surveillance allowed for the undetected persistence and evolution of this potentially pandemic strain for many years.”

Read more….