As of April 1, 2024, there have been cases of HPAI in dairy cattle confirmed in Texas (7), Kansas (2), Idaho, New Mexico (1), and Michigan (1). There is significant evidence that migratory waterfowl are the source of infection to dairy cows. Cow-to-cow spread is highly suspected, but the specific mode(s) of transmission (e.g., direct contact, inhalation, fomite, ingestion, vector) have not been determined. Follow the most recent updates about HPAI in dairy cattle from the USDA here.
What is HPAI?
Highly Pathogenic Avian Influenza, also known as avian flu or bird flu, is a disease caused by infection with avian Type A viruses. This virus is spread naturally among wild aquatic birds, but can infect other birds such as poultry or other animals. This virus is deadly to poultry, leading to high biosecurity measures with egg-laying or meat birds. While HPAI can infect humans, it is rare.
What does HPAI look like in dairy cattle?
Symptoms that have been seen include a drop in milk production, thickened or colostrum-like milk, appetite loss, manure inconsistencies, or a low-grade fever. Infected cows often show symptoms for 7-10 days before recovering. About 10% of cows do not recover fully and return to previous milk production, mainly those with the most severe symptoms. Those with severe symptoms have also been seen to develop secondary infections, such as mastitis, pneumonia, or salmonella. Most animals infected are cows in their second or greater lactation, in mid to late lactation.