The content describes the spillover of highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b virus from birds to dairy cattle in the United States. The affected cows displayed various clinical signs, including decreased feed intake, altered fecal consistency, respiratory distress, and decreased milk production with abnormal milk. Infectious virus and viral RNA were consistently detected in the milk of affected cows.
Immunohistochemistry and in situ hybridization revealed a distinct tropism of the virus for the epithelial cells lining the alveoli of the mammary gland in cows. Whole viral genome sequences recovered from dairy cows, birds, domestic cats, and a raccoon from affected farms indicated multidirectional interspecies transmissions.
Epidemiologic and genomic data also revealed efficient cow-to-cow transmission after apparently healthy cows from an affected farm were transported to a premise in a different state. These findings demonstrate the ability of the HPAI H5N1 clade 2.3.4.4b virus to cross species barriers and establish transmission at a non-traditional interface.
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by Leonardo C. ... at www.nature.com 07-25-2024
https://www.nature.com/articles/s41586-024-07849-4Deeper Inquiries