Avian influenza, also called bird flu, is an infectious disease of birds that is occasionally transmitted to human beings. The disease is caused by the type A influenza virus. Waterfowl, including wild ducks, sea birds, and shore birds, naturally carry this virus but generally do not develop the disease itself. But infected domestic birds, such as chickens, turkeys, and ducks, are likely to develop a rapidly fatal form of the disease. A number of human beings have also died from avian influenza.