A recent publication* evaluated transmission of H5N1 influenza among dairy cattle in the U.S.  The stochastic model based on 36,000 dairy herds in the continental U.S. attempted to quantify the extent of infection.  As of January 2025, when the article was submitted for peer review, the authors concluded that the infection is under-reported and that outbreaks will increase in Arizona and in Wisconsin.  The model suggests continuing cases associated with movement of dairy cattle coupled with inadequate programs of surveillance and restriction of transport.

Persistence of bovine influenza H5N1 in dairy cattle represents a danger to the poultry industry as confirmed by the 2024 outbreak of highly pathogenic avia influenza (HPAI) in western Michigan and the possibility of cases in Colorado and more recently in Arizona.  Failure to control and suppress bovine influenza will represent an ongoing risk to egg producers given movement of personnel between dairy herds and poultry flocks.  Common feed mills with non-dedicated delivery vehicles represents a risk of cross-industry infection. Proximity of large dairy and poultry farms could result in transmission of HPAI given the possibility of aerogenous spread of virus from large dairy installations to power-ventilated egg-production complexes.

*Rawson, T. et al A mathematical model of H5N1 influenza transmission in U.S. dairy cattle. Nature Communications doi.org10.1038/s41467-025-59554-z April 2025.