H5N1 influenza has now been detected in pigs. This was something virologists had been worrying about ever since this highly pathogenic strain of bird flu started its rapid global spread in 2020. But why were we worrying specifically about pigs?

Birds and humans have different types of receptors in their respiratory tract that flu viruses attach to, like a lock (receptors) and key (virus). The attachment of the virus allows it to invade a cell and the body and cause illness. Avian flu viruses are adapted to birds, and spread easily among birds, but not in humans.

The recent detection on an Oregon farm raises the risk of the influenza virus acquiring mutations that lead to a pandemic pathogen.

H5N1 bird flu was confirmed in a pig on a backyard farm in Oregon, the first detection of the virus in swine in the country, the U.S. Department of Agriculture said on Wednesday.

A pig at a backyard farm in the US state of Oregon tested positive for H5N1 avian flu, the first such case in the United States, officials said Wednesday.