>>22518484
All flu strains have an animal reservoir, that's why they can't be eradicated.
Plus it's a mutating virus.
From Leo AI on Brave
Animal Reservoirs of Flu
Influenza viruses are known to have multiple animal reservoirs, with wild aquatic birds and shorebirds forming the natural virus reservoir for influenza A viruses. These birds are the primary hosts for all influenza virus subtypes and almost all possible hemagglutinin/neuraminidase combinations.
Ducks, in particular, are especially susceptible to harboring influenza viruses without showing overt clinical signs of disease, making them common mixing vessels for bird flu strains. This characteristic allows them to serve as a reservoir for the virus, facilitating the spread of different influenza strains.
Pigs are also susceptible to influenza B virus (IBV) and may serve as a natural reservoir. Additionally, antibodies against IBV have been isolated from horses and pigs in Japan and from dogs in Taiwan. However, no evidence of seal-to-human transmission of influenza B virus has been reported, and no novel seal-reservoired IBV strains have been detected.
In summary, wild aquatic birds, shorebirds, and ducks are key reservoirs for influenza A viruses, while pigs can serve as a natural reservoir for influenza B viruses.