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USDA Confirms Bird Flu in Wisconsin Dairy Herd

12/20/2025

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Summary

Story summary

On December 19, 2025, the U.S. Department of Agriculture confirmed a case of highly pathogenic avian influenza in a Wisconsin dairy herd.
The virus is H5N1 clade 2.3.4.4b genotype D1.1.
It represents a wildlife-to-cattle spillover.
USDA said there is no risk to health or the milk supply because pasteurization kills the virus.
Senators urged U.S. President Donald Trump’s administration to develop a bird flu vaccine for livestock.

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Story summary

On December 19, 2025, the U.S. Department of Agriculture confirmed a case of highly pathogenic avian influenza in a Wisconsin dairy herd.
The virus is H5N1 clade 2.3.4.4b genotype D1.1.
It represents a wildlife-to-cattle spillover.
USDA said there is no risk to health or the milk supply because pasteurization kills the virus.
Senators urged U.S. President Donald Trump’s administration to develop a bird flu vaccine for livestock.