- The USDA has mandated testing of the national milk supply to identify dairy herds infected with bird flu.
- The order targets bulk milk transporters and dairy processors, with initial testing in six states starting December 16.
- Infected cows shed the virus through their mammary glands, raising concerns about raw milk consumption.
- Commercial pasteurization inactivates the virus, making pasteurized milk safe to drink.
- Scientists warn that the H5N1 strain could evolve to spread more easily among humans, highlighting the need for continued vigilance.
In response to the rapid spread of bird flu among dairy cows, the U.S. Department of Agriculture (USDA) has announced a federal order requiring the testing of the national milk supply. The mandate, which targets bulk milk transporters and dairy processors, aims to identify infected herds and prevent further transmission of the virus.
As of Thursday, the H5N1 strain of bird flu has affected 718 dairy herds across 15 states. The new order, first reported by Reuters, will take effect on December 16, starting with six states: California, Colorado, Michigan, Mississippi, Oregon, and Pennsylvania.
Key Measures Under the USDA Order
Under the mandate, entities handling raw milk—such as bulk milk transporters and dairy processors—must collect and share samples with the USDA upon request. This initiative is designed to quickly pinpoint affected herds and curb the virus’s spread.
Agriculture Secretary Tom Vilsack emphasized the importance of the order in a press release, stating, “This will give farmers and farmworkers better confidence in the safety of their animals and ability to protect themselves, and it will put us on a path to quickly controlling and stopping the virus’ spread nationwide.”
In addition to testing, dairy herd owners with cattle that test positive for bird flu must provide information to aid in surveillance efforts. This builds on an earlier USDA order from April, which required lactating dairy cows to be tested for bird flu before interstate transport and mandated reporting of positive cases by private labs and state veterinarians.
Rising Concerns Over Bird Flu in Livestock
The USDA’s action reflects growing urgency to address the spread of bird flu among livestock, which scientists warn could pose a broader risk to human health. While the virus primarily affects birds, its transmission to mammals—including cows, raccoons, and cats—has raised alarms.
Research suggests that the virus spreads efficiently between mammals, likely through raw milk, as infected cows shed large amounts of the virus through their mammary glands. Despite warnings from the Centers for Disease Control and Prevention (CDC) about the risks of consuming raw milk, its popularity has continued to rise.
Safety of Commercial Milk
Several studies have confirmed that commercial pasteurization—a process that uses heat to treat milk—effectively inactivates the bird flu virus, making pasteurized milk safe for consumption. However, raw milk remains a concern.
In November, California health officials detected bird flu in multiple batches of raw milk from a local dairy farm, prompting a recall of the farm’s raw milk and cream products. No human cases have been linked to these products, but the incident underscores the potential risks of consuming untreated milk.
Human Cases and Public Health Implications
To date, the CDC has confirmed 58 human cases of bird flu in the U.S., most of which involved exposure to infected cattle or poultry. On Friday, Arizona reported its first two cases in poultry workers. Symptoms have generally been mild, including pinkeye, coughs, or sneezes, though some cases may be asymptomatic. The CDC recommends testing for anyone exposed to the virus.
While there is no evidence yet of human-to-human transmission, scientists are concerned that the H5N1 strain could evolve to spread more easily between people, potentially sparking a pandemic. A study published in Science on Thursday found that a single mutation in the bird flu strain circulating in dairy cows could enable it to spread more efficiently among humans.
Looking Ahead
The USDA’s testing mandate is a critical step in monitoring and controlling the spread of bird flu among livestock. By identifying infected herds and preventing further transmission, the order aims to protect both animal and human health.
As research continues, scientists and public health officials stress the importance of vigilance and adherence to safety guidelines, particularly regarding the consumption of raw milk. With the potential for the virus to evolve, proactive measures like the USDA’s testing program are essential to mitigating risks and safeguarding public health.
