Influenza in Animals
CDC has compiled two tables that showing the different hemagglutinin and neuraminidase subtypes and the species in which they have been detected.
Influenza A viruses are found in many different animals, including ducks, chickens, pigs, whales, horses, seals and cats.
Influenza B viruses circulate widely only among humans.
Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: the hemagglutinin (H) and the neuraminidase (N). There are 18 different hemagglutinin subtypes and 11 different neuraminidase subtypes. All known subtypes of influenza A viruses have been found among birds, except subtype H17N10 and H18N11 which have only been found in bats.
While it is unusual for people to get influenza infections directly from animals, sporadic human infections and outbreaks caused by certain avian influenza A viruses have been reported.
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