Wild bird sparked flu outbreak in cows and other animals
Researchers have traced the recent spread of highly pathogenic avian influenza (HPAI) in U.S. dairy cattle to a single spillover event from a wild bird. The study, led by Thao-Quyen Nguyen and team, found that the virus likely jumped from a bird to a cow in Texas around mid-to-late 2023, leading to months of undetected transmission between cows.
The specific virus strain involved is H5N1 clade 2.3.4.4b, which has shown pandemic potential. This strain has already infected wild birds, poultry, mammals, and even some humans globally. In 2024, it was detected in dairy cattle across several U.S. states, a rare and alarming development.
Researchers analyzed genetic data from over 100 virus variants and new outbreak reports. Their findings show that infected or presymptomatic cattle helped spread the virus across state lines—from Texas to North Carolina, Idaho, Michigan, Ohio, Kansas, and South Dakota.
After entering cattle, the virus didn’t stop. It spread to poultry, cats, raccoons, and wild birds like grackles and pigeons. Genetic changes found in the virus suggest it is becoming better adapted to mammals, which raises concerns about its potential to infect more species, including humans.
The study highlights the importance of cooperation among animal and public health organizations to prevent further spread and reduce pandemic risks.
As Nguyen writes, “Influenza A virus is a transboundary pathogen that requires coordination… to improve host health and reduce pandemic risk.”
For public safety, early detection and coordinated response are key.
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