Content Summary : FAQs on Avian Influenza and “bird flu” for Michigan Residents What is avian influenza and “bird flu”? Like humans, birds have naturally occurring influenza (flu) viruses. There are numerous subtypes (144) of avian influenza viruses that are carried by wild bird species throughout the world, but these viruses do not cause disease in these birds. Occasionally, some of these viruses can infect domestic birds such as poultry, but typically we do not see direct transmission of avian influenza viruses from birds to humans. “Bird flu” is a non-scientific term that refers to a specific virus (H5N1) that has been present in domestic birds in Asia since 1997. This particular virus has been associated with human infections and deaths. What types of birds does avian influenza infect? Naturally occurring avian influenza viruses in wild birds are generally associated with waterfowl (ducks and geese), gulls, and some species of shore birds and typically do not cause illness in these birds. The viruses occasionally “jump” from these wild birds to domestic birds such as chickens, quail and turkeys. In some cases these viruses can cause severe disease in domestic birds, but in general this requires viral adaptations via genetic mutations that occur over time in domestic bird populations. This is the case with the highly pathogenic H5N1 virus (“bird flu”) which has been circulating in domestic birds in Asia at least since 1997. Although this virus probably originated in wild birds, it has mutated and adapted to domestic poultry.