What kinds of wild birds primarily carry avian influenza?
Most avian influenza viruses have been isolated from wild waterfowl (ducks, geese, and swans) and shorebirds (wading birds), gulls and terns. With rare exceptions, the thousands of flu isolates found in wild birds have been low pathogenic avian influenza and have rarely caused signs of illness in wild birds. The occurrence of avian influenza in wild ducks in North America reaches its height in late summer and early fall. At other times of the year, infection rates are usually less than 1 percent. In shorebirds, infection rates are highest during the spring migration, although in comparison with waterfowl, their infection rates are much lower. Can migratory birds bring highly pathogenic avian influenza (HPAI) H5N1 to North America? Migratory birds usually travel thousands of miles over the same routes in their annual migrations. In the Northern Hemisphere, birds begin moving south during August and September of each year. North American migratory birds that spend the winter in Asia may