Avian flu could strike Asian poultry markets outside China

Particularly in cities near water, H7N9 influenza could take hold, researchers predict

BIG RISKS  H7N9 influenza has a higher chance of spreading to humans in urban areas close to water. Yellow indicates the lowest predicted risk of infection and purple the highest. Taller spikes indicate higher risk. 

M. Gilbert et al., Nature Communications 2014

If it spreads beyond China’s borders, the H7N9 avian influenza virus could take hold in Vietnam’s Mekong and Red River deltas, the Bengal region of India and in parts of the Philippines and Indonesia, a new study predicts.

The virus has infected 449 people in China, many of whom had visited live poultry markets. “We don’t know where it will be introduced next,” says Marius Gilbert, an epidemiologist at the Université Libre de Bruxelles in Belgium. But he and his colleagues analyzed environmental conditions at 8,943 live poultry markets in China to determine which are shared by 263 markets linked with human cases. Places with a high density of poultry markets, especially urban areas, are most at risk of having the virus establish itself and spread to people, Gilbert and his colleagues report June 17 in Nature Communications.

Other factors that may give the virus a chance to thrive include proximity to open water and rice paddies, high human population density, and a large number of domestic ducks and chickens. Gilbert speculates that poultry trade with infected areas could move the virus from place to place.

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

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