Avian flu has infected dairy cows in more than a dozen states – a microbiologist explains how the virus is spreading

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Jenna Guthmiller, University of Colorado Anschutz Medical Campus

(THE CONVERSATION) The current strain of avian flu, H5N1, is responsible for the culling of millions of domestic birds and has sickened more than a dozen farmworkers in 2024, most recently in Colorado.

The Conversation U.S. asked immunologist and microbiologistJenna Guthmiller from the University of Colorado Anschutz Medical Campus to explain the historical roots of H5N1, its mode of transmission and how to avoid coming into contact with it.

What is H5N1?

H5N1 is a subtype of influenza A viruses. Other commonly known influenza A virus subtypes include H1N1 and H3N2, which cause seasonal outbreaks in humans.

Unlike H1N1 and H3N2, H5N1 largely infects wild birds, with waterfowl such as ducks and geese being the natural reservoirs for H5N1 viruses. Most H5N1...