Scientists sound alarm over unprecedented lethality of bird flu virus and its ability to spread from poultry and wild birds

U.S. scientists are calling for urgent action on a current strain of bird flu that they say is dangerously different from previous outbreaks of the disease that have killed birds in large numbers around the world.

A new study led by a team of researchers at the University of Maryland found that the current strain of bird flu that is killing millions of birds is "different" than in past decades and is killing birds in unprecedented numbers

Mullinax said, "This highly pathogenic virus is wiping out everything in numbers we've never seen before."

The study, published in the journal Conservation Biology, was conducted by tracking the arrival and progress of the deadly avian influenza outbreak in North America to see how the latest outbreak compares to previous ones.

The researchers analyzed five different data sources that had information on the presence of avian influenza in wild birds and poultry in the United States and Canada, as well as a global database with information from 2014 to 2023. Unlike the 2015 H5N8 avian influenza epidemic, the H5N1 avian influenza epidemic at the end of 2021 caused mass mortality in wild birds, which made the highly pathogenic virus more difficult to eradicate. "Unlike H5N8, this disease severely affects wild birds," said Johanna Harvey, lead author of the study and a postdoctoral researcher at the University of Maryland.

It's hard to estimate how many birds in wild populations are truly affected, but we're seeing huge disease impacts on raptors, seabirds and colonial nesting birds. We have the most poultry deaths from avian flu right now, so that's the worst-case scenario. The researchers found that about 58 million poultry were infected or killed in the United States to stop the spread of the infection, and 7 million in Canada.

The recent bird flu outbreak may have shifted from the seasonal disease of the past to a year-round disease.

Bird flu outbreaks in 2015 typically occurred in the fall, when farmers could be prepared and had more time to recover from losses. But recent outbreaks have occurred year-round, in the summer for wild birds and in the spring and fall for domesticated poultry.

The researchers concluded that the disease's lethal effects on wild birds and the change from seasonal to year-round infection may portend a dangerous change in avian influenza in the United States. In addition, avian influenza is likely to become an endemic disease, which could affect food security and the economy.