WASHINGTON, D.C.: To contain the spread of bird flu, U.S. dairy farmers have banned visitors, cut down trees to discourage wild birds from landing, and disinfected vehicles driving on their land.
After the U.S. Department of Agriculture (USDA) reported infections of highly pathogenic avian influenza (HPAI) in dairy herds in North Carolina, Texas, Kansas, Ohio, Michigan, Idaho, and New Mexico, South Dakota became the eighth state to confirm its presence this week.
The USDA said that while the first cases appear to have been introduced to herds in Texas and Kansas by wild birds, transmission among cattle was also possible.
Agricultural officials in Michigan and Ohio have said that infected herds in their states received cattle from Texas.
Karen Jordan, who raises about 200 dairy cattle in Siler City, North Carolina, said, “Think of our farm now as a gated community for cows. Only the most essential person can get past the gate.”
Since 2022, bird flu has decimated poultry flocks worldwide and infected many types of mammals.
However, the risk to humans remains low, said the U.S. Centers for Disease Control and Prevention, which nonetheless urged states for plans to test and treat potentially impacted farm workers.
The USDA said that while bird flu is lethal to poultry, cows appear to recover, and the outbreaks in dairy herds primarily affect lactating cows. It called for reduced milk production and encouraged farmers to isolate sick animals while keeping their milk out of the food supply.
The USDA said that bird flu has been discovered in unpasteurized milk samples, but pasteurized milk is safe.
While not issuing quarantine orders for infected dairy herds, the agency has recommended minimizing the movement of cattle and testing milk samples from lactating cows if they must be moved.
The agency advised farmers to pay “special attention to good milking practices, such as equipment disinfection.”
“We cannot rule out other possible modes of HPAI transmission, including equipment,” the USDA said in an email.
Farmers are also trying to keep wild birds away from feed supplies, but it is difficult.