Swine Flu Source Traced to Birds and People; Don’t Blame Pigs

By Jason Gale

May 4 (Bloomberg) — Pigs are getting slaughtered to prevent the spread of a new strain of flu. Ducks and humans may be more to blame.

While the new H1N1 strain that threatens to spark a pandemic evolved in swine, its ancestors came from waterfowl, says Richard Webby, who has analyzed the virus’s genetic code.

Viruses that circulate in aquatic birds are the genetic ancestors of all pandemic-causing influenza, including the 1918 Spanish flu blamed for killing 50 million people, according to Webby, head of a World Health Organization Collaborating Center in Memphis, Tennessee, that studies the ecology of influenza. Pigs are a mixing vessel for human and bird flu viruses because they are susceptible to both avian and mammalian strains.

“There is some quite good evidence that avian viruses get into swine barns through the practice of using pond water to wash down the barns,” said Webby, 38, who is also a virologist at St. Jude Children’s Research Hospital in Memphis.