Oregon confirms its first bird-flu case in dairy cattle
The infection was discovered through Oregon’s routine milk-monitoring programme, which introduced weekly testing across the state in late 2024. Agriculture officials are investigating how the cattle became infected. Ryan Scholz, the department’s state veterinarian, said the surveillance system had detected the infection promptly and enabled a rapid response involving state and federal partners. He described the detection as significant but unsurprising, given the virus’s spread through American dairy herds.
The Oregon Health Authority is monitoring workers who had contact with the infected cattle and will continue checking for symptoms, according to Melissa Sutton, its medical director for respiratory viral pathogens. Sutton said appropriate personal protective equipment keeps workers’ risk low. She said the public-health response prioritises prompt testing and treatment when symptoms appear, with the aim of preventing severe illness.
Earlier this month, a dairy worker in Washington’s Yakima County died after becoming infected. Washington health officials said the worker had underlying medical conditions. Deaths associated with bird flu in humans are very rare. Two other Yakima farmworkers contracted the virus, but neither became severely ill or required hospital care. Across Washington, at least 41 dairy farms have returned positive bird-flu tests during the past 30 days.
The Centers for Disease Control and Prevention assesses the risk to the general public as low, while people whose work brings them into close contact with cattle or poultry face a greater likelihood of infection. Officials say milk and other dairy foods remain safe to consume because pasteurisation inactivates the virus. Milk produced by sick animals is diverted away from food use or destroyed to keep it out of the food supply.
The first identification of bird flu in dairy cattle came in March 2024. Detections have subsequently occurred in several states, among them Washington, Idaho and California. Evidence indicates that transmission within dairy herds occurs chiefly between cows. In poultry operations, including commercial farms and backyard flocks, birds generally acquire the infection from migrating wild waterfowl.
The virus involved has also affected millions of poultry birds across the United States since 2022. According to the US Department of Agriculture, Oregon’s affected birds include more than one million chickens kept commercially or in backyard flocks. Commercial poultry operations and backyard flocks account for most of the state’s known bird-flu infections.
Avian influenza can also infect other animals, including wild mammals. Oregon has recorded the virus in at least one pig on a non-commercial farm, as well as in skunks, raccoons and rodents. At least five cats in the state were found to have the virus last year.
