The Biden administration on Wednesday said that it would begin requiring dairy cows moving across state lines to be tested for bird flu, which has been spreading in herds for months. The new policy is part of a growing effort to stamp out the spread of a virus that federal health officials have sought to reassure Americans poses little risk to people so far.
The new order, issued by the Department of Agriculture, says that lactating cows must test negative for influenza A viruses, a class that includes bird flu, before they are transported. The owners of herds with positive tests will need to provide data on the movements of the cattle to help investigators trace the disease.
The testing will help protect the livestock industry, limit the spread of the virus and “better understand this disease,” Mike Watson, a senior Department of Agriculture official, told reporters in a press briefing Wednesday morning.
Since a highly contagious form of bird flu was detected in the United States in 2022, federal officials have sought to reassure Americans that the threat to the public remained low, even as the virus infected a growing number of mammals. Federal regulators on Tuesday announced that inactive viral fragments had been found in pasteurized milk, a suggestion that the virus was likely spreading much more widely among cattle than previously known.
Dr. Nirav Shah, the principal deputy director of the Centers for Disease Control and Prevention, told reporters on Wednesday that there were no changes in the genetic makeup of the virus that would allow it to spread easily among people. So far, Dr. Shah said, states have been monitoring 44 people who were exposed to the virus and are being monitored for infection.
As of Wednesday, the outbreak had spread to 33 herds in eight states, according to the U.S.D.A. But just one human infection has been reported, in a dairy worker in Texas who had direct contact with sick cows. The case was mild.