As a second strain of bird flu has spread to dairy cows, influenza experts tell Newsweek that consumers should not be concerned about drinking pasteurized milk.
Newsweek reached out via email to the U.S. Department of Agriculture (USDA) for comment on Thursday.
Why It Matters
On Wednesday, the USDA confirmed the detection of avian influenza in dairy cattle in Nevada, marking the second strain found in cows since last March.
The virus’s second jump to cows raises concerns about its potential to mutate and its growing impact on animal and public health, as well as the economy, particularly amid an egg shortage.
What To Know
The identification of the H5N1 clade 2.3.4.4b (genotype D1.1) strain in cattle occurred after state tracing and initial testing under the USDA’s National Milk Testing Strategy. The strategy came out of a December order to help monitor the spread of bird flu in dairy cows.
Maurice Pitesky, a veterinarian at the University of California, Davis, who specializes in poultry health and food safety, classifies the new detection as “significant” because it “demonstrates that the virus can be transmitted by waterfowl to dairies.”
Pitesky told Newsweek Thursday that this is notable since a “majority of the outbreaks on dairies were believed to be farm-to-farm transmission via movement of equipment/animals.”
He added that this development will be a “significant challenge for the dairy industry, as physical biosecurity to prevent interaction between infected wild waterfowl and dairies is lacking.”
Virologist Melanie Ott of the Gladstone Institute of Virology and Immunology called the jump “very concerning because it underscores that cows are a huge animal reservoir in which the virus can evolve and persist. Cows, unlike birds, do not die from the infection, offering more opportunities for mutations and adaptation during prolonged viral replication.”
Ott also said the appearance of this second strain “is especially concerning as it resembles the strain that circulates in birds and has caused severe disease in people.”
The U.S. has over 9.3 million dairy cows, according to the USDA, and as of Wednesday 957 herds have been affected by bird flu.
In the U.S., bird flu has sickened 67 people and caused one death. Since the outbreak began in 2022, all 50 states have reported infections and hundreds of millions of birds have been affected.
Is Pasteurized Milk Safe to Consume?
Virologists and animal health experts told Newsweek that consumers should avoid raw milk, echoing standard guidance from leading food safety and health agencies, including the U.S. Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA) and the USDA. To prevent foodborne illnesses, that guidance warns against drinking raw milk.
“A real risk [of contracting the virus] exists when consuming raw milk,” Ott told Newsweek.
Nearly all milk consumed in the U.S. and sold in grocery stores is pasteurized, a process that kills harmful bacteria and extends shelf life. The FDA reports that 99 percent of the U.S. commercial milk supply follows the FDA’s Pasteurized Milk Ordinance, ensuring safety protocols are followed.
In late September, the FDA and USDA co-signed letters to members of the dairy industry saying that “pasteurization is effective at inactivating H5N1 in raw milk as it is for the pathogens against which we began pasteurizing raw milk 100 years ago.”
Many in the scientific community agreed with the findings. The director of the Wisconsin Veterinary Diagnostic Laboratory, Keith Poulsen, told Newsweek on Thursday: “Pasteurization is 100 percent effective, and H5N1 is not a food safety issue.”
Another expert, Suresh Mittal, a professor of virology and infectious diseases program leader at Purdue University, reiterated that pasteurized milk is safe to consume.
He told Newsweek that “the U.S. milk supply is safe since the cattle influenza virus gets completely inactivated by pasteurization. No infectious virus particles have been detected so far.”
Is Cow Milk Cheese Safe to Consume?
Cheese is a slightly different case. Not all cheeses are made from pasteurized milk and therefore don’t necessarily go through the proper heating process that kills various bacteria and viruses.
Poulsen told Newsweek that “the jury is still out on aged artisanal raw milk cheeses,” noting that “certainly fresh raw milk cheese represents a risk for foodborne disease.”
There are currently no reported cases of bird flu transmitted through raw milk cheese.
Poulsen reiterated that bird flu present in cattle is “an animal disease problem” rather than a concern about food sources.
What People Are Saying
Keith Poulsen said that while the public health risk is low, “the longer [the] virus is circulating in domestic animals, the more chances for exposure, mutation and increased virulence [and a potential pandemic].”
Suresh Mittal said bird flu “has the potential to mutate into a pandemic influenza virus. Whether it will happen or not is highly uncertain.”
Melanie Ott said: “The only testing mandated for cows by USDA occurs when cows cross state lines. Otherwise, guidelines exist for states to test milk and herds. The true extent of virus circulation in cows remains therefore unclear.”
What Happens Next
The CDC is continuing its surveillance efforts and is working with states to monitor individuals exposed to infected animals. But it maintains that the “current public health risk is low.”
The post Can You Get Bird Flu From Drinking Milk? What to Know as Cows Are Infected appeared first on Newsweek.
