In the month since federal authorities announced an outbreak of bird flu on dairy farms, they have reassured the public that the spate of infections does not impact the nation’s food or milk supply, and poses little risk to the public. However, an obscure online update from the Department of Agriculture revealed evidence of the virus spreading among cows and from cows to poultry. Officials in North Carolina have detected bird flu infections in a cattle herd with no symptoms, indicating that the spread may be more widespread than previously thought. The U.S.D.A. has not required farms to test cattle for infection but is now beginning to reimburse farms for testing cows without symptoms.
Federal officials have shared limited genetic information about the virus with scientists and other countries to understand how the virus might be evolving as it spreads. They are not monitoring infections in pigs, which are effective hosts for evolving flu viruses and are often kept in proximity to cattle. The safety of milk is a concern, although pasteurized milk has been deemed safe by the U.S.D.A., FDA, and CDC. The F.D.A. is conducting tests to see if the pasteurization process eliminates the virus, but results are pending.
Some experts have criticized the agencies for asserting that the milk is safe before having the necessary data. The federal response to the outbreak has been compared to early missteps during the pandemic, with concerns about communication strategies. The U.S.D.A. has been working on investigations with a team of experts but has been urged to share more information with outside scientists to help contain the virus. Part of the problem may be the conflicting roles of the U.S.D.A. in regulating and promoting agriculture.
The outbreak of bird flu in dairy cows has spread to 32 herds in eight states, with uncertain origins. The virus, called H5N1, appears to only affect lactating cows temporarily, and has not affected calves, pregnant heifers, or beef cows, with no reported deaths. There has been one instance of the virus spilling back from cows to poultry in Texas. The U.S.D.A. is not testing pigs for infection, which could play a role in surveillance and the potential evolution of the virus.
The testing recommendations from the U.S.D.A. have been criticized for only reimbursing a pool of visibly ill animals, potentially missing asymptomatic infections. Widespread testing is crucial for understanding the scale and transmission of the virus early in outbreaks. Some state health departments and farmers have grown frustrated with the federal approach and are taking independent measures to test for the virus. Dairy farmers are dealing with economic challenges and are concerned about potential losses if the outbreak affects their business.
Federal officials are working on developing vaccines for cattle to protect them from H5N1, but the timeline for these vaccines is uncertain. There are hopes that the virus will eventually burn itself out, but preparations are being made for the possibility of the outbreak becoming a long-term problem. Overall, there are concerns about communication strategies, testing protocols, and the potential impact of the bird flu outbreak on the dairy industry and food supply.
