The initial case of highly pathogenic avian influenza (HPAI) was reported in December of last year at an Oregon farm. Earlier this year, the first case at a commercial farm was detected at a poultry farm in California. Since then, the disease has appeared at an additional five commercial poultry farms.

Reported cases of HPAI in the US initially appeared to be restricted to the Pacific region of the country, but it has made its way east this month, with confirmed cases at four commercial turkey farms in Missouri, Minnesota and Arkansas. In all, 14 flocks have been infected in the US since December 2014.News of the outbreaks has prompted dozens of countries, including those in the European Union and China, to ban poultry imports from the Pacific Northwest.