Animal Health Update: Influenza A Viruses including Avian Influenza and Bovine Influenza

Influenza A Virus

Updated April 15, 2024

Highly Pathogenic influenza is an infectious viral disease caused by influenza A viruses. Avian influenza A viruses spread naturally among wild, migratory birds (e.g., waterfowl) and can infect domestic birds (e.g., chickens, turkeys, pheasants, quail, domestic ducks, geese, and guinea fowl) and other animal species. Bovine influenza has recently been diagnosed in dairy cattle herds and is from the same virus subtype as avian influenza and is also categorized as influenza A.

Influenza A viruses are classified into two categories based on the severity of illness: low pathogenic influenza A viruses and highly pathogenic influenza A viruses. Both high and low pathogenic viruses spread easily among wild, migratory birds. Some virus strains can infect domesticated birds and mammals both wild and domestic. Infections caused by influenza A viruses can be highly pathogenic and are highly contagious and often deadly in birds. While most influenza viruses do not normally infect people, human infections have occurred with some avian influenza types and are most often associated with direct or indirect contact with infected birds or animals.

Influenza A is not a food safety concern. Influenza viruses are easily destroyed by heat and cooking food to the proper internal temperatures will kill bacteria and viruses, including influenza viruses. In the United Safety, federal agencies have continuous inspection requirements for all animals and rigorous programs for monitoring and preventing zoonic diseases, such as influenza A. Any animal exposed to influenza A or shows signs of illness are immediately quarantined and does not enter the food supply. In addition, only milk from heathy animals is authorized for distribution into interstate commerce for human consumption. Pasteurization, or high heat treatment, kills harmful microbes and pathogens in milk, including the influenza virus. Pasteurization is required for any milk entering interstate commerce. Regardless, any milk from ill (symptomatic) animals is diverted or destroyed so that it does not enter the human food supply.