Why dangerous bird flu is spreading faster and farther than first thought in U.S. cattle
Infections could have been 'flying under our radar for months,' researcher says

Lauren Pelley, Amina Zafar · CBC News · Posted: Apr 27, 2024 4:00 AM EDT | Last Updated: April 27
This story is part of CBC Health's Second Opinion, a weekly analysis of health and medical science news emailed to subscribers on Saturday mornings. If you haven't subscribed yet, you can do that by clicking here.

A dangerous type of bird flu virus discovered in the lung of a U.S. dairy cow that didn't show symptoms. Viral particles identified in processed, pasteurized milk. Genetic sequences showing distinct changes in this H5N1 strain that's been rapidly spreading throughout American cattle.

Those were just a handful of the rapid-fire developments this week as an unprecedented H5N1 outbreak among U.S. dairy cattle continued to evolve.

Scientists now warn this form of avian influenza is likely more widespread in cows, and was transmitting for longer than official reports suggest. And while American officials are ramping up testing — all in an effort to keep sick cows from being moved between states — others say we're already several steps behind the spread of a disease that could pose a major threat to human health.

Michael Worobey, a researcher from B.C. who's now head of the department of ecology and evolutionary biology at the University of Arizona, said these cattle infections may have been "flying under our radar for months," providing ongoing opportunities for this virus to acquire adaptations that could lead to a flu pandemic. "I think, in many ways, this is the biggest news story in the world right now."
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https://www.cbc.ca/news/health/h5n1-second-opinion-april-27-cattle-1.7185165