The complexity of H5N1 transmission in dairy farms
A recent bioRxiv preprint (not yet peer reviewed) examines the transmission dynamics of HPAI H5N1 on 14 dairy farms in California. Traditionally linked to poultry, the virus’s detection in cattle highlights concerns about novel transmission routes and zoonotic risk.
Environmental sampling revealed:
Airborne spread: H5N1 RNA and infectious virus were found in aerosols within milking parlors and in cows’ exhaled breath during milking.
Waterborne contamination: Viral RNA was detected in wastewater, suggesting runoff may aid environmental persistence.
Subclinical intramammary infections: Milk samples showed widespread infection without overt mastitis, with heterogeneous distribution across udder quarters over time.
Genomic analysis revealed hemagglutinin mutations linked to altered receptor binding, indicating in-host viral evolution. The findings support multiple transmission pathways, including aerosols and contaminated water, as key contributors to H5N1 spread in dairy settings.
