Avian influenza, or "bird flu," is a contagious viral disease of domestic and wild birds. The disease is caused by influenza type A viruses and varies in severity depending on the strain and species affected.
Highly pathogenic avian influenza (HPAI) strains are fatal for domestic poultry and can wipe out entire flocks within days. It is a major threat to the poultry industry, animal health, trade and the economy worldwide. Since January 2022, highly pathogenic avian influenza H5N1 has affected more than 97 million birds across 48 states.
Dairy cases reported
In March 2024, HPAI H5N1, also called H5N1 bovine influenza, was confirmed on dairy premises. Since the initial confirmation, the virus has spread to more than 145 dairy herds across 12 states and the cases continue to rise.
Infected dairy cattle present with different clinical signs and symptoms than poultry, such as a decrease in milk production, drop in feed consumption, and thickened or clotted milk. Dairy cattle typically recover from clinical signs after approximately two weeks and most can go back into milk production.
A United States Department of Agriculture (USDA) national epidemiological survey of affected dairy premises indicated that enhanced biosecurity measures are needed to decrease the spread of the virus. Factors that appear to be of greatest risk for introduction into dairy premises may be mitigated through enhanced biosecurity, increased animal testing and potentially through within-state animal movement restrictions, if they can be implemented without impacting animal welfare.
Whole genome sequencing (WGS) of viruses from positive dairy and poultry premises identified Eurasian lineage goose/Guangdong clade 2.3.4.4b, genotype B3.13 on both premises. Because some HPAI-affected dairy cattle were undetected and nonclinical at the time of movement and had been shipped to a dairy near a later affected poultry flock, it suggested indirect transfer of the virus from the dairy to the poultry premises.
Time to work together
The poultry industry has battled HPAI for many years now, which has led to a significant amount of research in areas such as enhanced biosecurity methods, viral transmission, pathogenesis, surveillance, environmental sampling, depopulation and repopulation, disposal, cleaning and disinfection and other areas.
There are valuable lessons that have been learned through battling with HPAI in poultry that may assist the dairy industry in controlling and eliminating the disease. Further, due to the nature of how the virus mutates and transmits, there have been human cases reported and other events in a multitude of mammals.
Information sharing and collaboration are needed to ensure the sustainability of dairy products, poultry and eggs. It is crucial that all animal agriculture sectors get involved and proactively work together to combat this national agricultural threat.
