Highly-pathogenic strains of avian influenza have wiped out poultry flocks in 12 different states, resulting in culling of about two million birds according to U.S. and international organizations.
The latest outbreaks are in Maryland and South Dakota.
Some of the outbreaks have claimed only a few birds in backyard flocks, but a broiler farm in Missouri lost 246,000 birds.
A number of flocks are turkeys.
The disease is coming from migrating waterfowl. I can spread into barns on boots that tramp on bird droppings.