Trade of infected poultry most likely bird flu route

The researchers, whose findings are published in the Proceedings of the National Academy of Sciences, studied how H5N1 avian influenza moved out of China, across Asia and Europe and into the Middle East and Africa.

They concluded that poultry trade was often the source, with migrating fowl then spreading it further.

“We conclude that the most effective strategy to prevent H5N1 from being introduced into the Western Hemisphere would be strict controls or a ban on the importation of poultry and wild birds into the Americas and stronger enforcement to curb illegal trade,” they wrote.

Genetic testing allowed most of the H5N1 outbreaks to be traced to the poultry trade, migratory birds or wild birds.

The findings point to the importance of surveillance programs for early detection of bird diseases like H5N1, they said, noting that Canada, Mexico and other countries import day-old chicks from other regions while the US does not.

Illegal trade in chicken feces for fertiliser and fish food could also be a source of the disease.

The World Health Organisation reports that the virus has infected 258 people and killed 153, mostly in Vietnam, Indonesia, Thailand and China.