Last year, more than 57 million birds, including poultry, perished in the U.S. from a surge of avian influenza (H5N1), a killer disease that has been increasingly effective in attacking wild birds, especially migrating waterfowl. Mallards and Canada geese seem to be the most susceptible. The disease, which has flared up sporadically since its discovery, as fowl plague, in 1878, is caused by infections that occur naturally in wild aquatic birds. These infections are transmitted to other birds, domestic and wild, through bodily discharges as well as through contact with contaminated surfaces.
Until last summer, Avian Flu has been seasonal, proliferating from September to March and then disappearing during the warmer months. The current outbreak, however, has not fallen off over the last two summers.