Avian Influenza (Bird Flu)
Avian influenza, first identified in Italy more than 100 years ago, affects birds. Migratory wildfowl, particularly wild ducks, are the natural reservoir. As with many animal diseases, humans can sporadically become infected under special conditions.
A strain of H5N1 avian influenza (Clade 220.127.116.11b) highly capable of causing disease in birds has been identified in wild and domestic birds in Illinois in 2022. The current strain of avian H5N1 circulating 2021-2022 is different than strains circulating in previous H5N1 outbreaks. So far, the current H5N1 avian influenza virus does not seem to infect people easily or cause severe illness in people. Only one human infection with the current H5N1 strain has occurred, an individual in the United Kingdom who raised birds infected with the virus. This individual did not develop symptoms.
This virus can cause high mortality in poultry. Migratory waterfowl, particularly wild ducks, are the natural reservoir. This H5N1 avian influenza virus is primarily a bird health issue. Although there have been no human cases of this type of avian influenza in the U.S., there is concern it could occasionally spread to individuals who have very close contact with infected live or dead birds.