After identifying traces of bird flu virus in grocery store milk, federal officials said Wednesday they “believe” the nation’s milk supply is safe and the virus has been neutralized through pasteurization.
“Heating milk to a specific temperature by pasteurization for a specific period of time is done to limit the activity of pathogens to a level that does not pose a risk to consumer health,” said Don Prater, Acting Director of the U.S. Food and Drug Administration. Center for Food Safety and Applied Nutrition.
However, Prater acknowledged that “no studies on the effects of pasteurization on HPAI (highly pathogenic avian influenza) viruses and bovine milk have previously been completed.”
Wednesday’s safety assurance follows a series of bird flu outbreaks on dairy farms in eight states. FDA scientists said they detected genetic material belonging to the current bird flu strain in pasteurized milk samples taken from supermarket shelves. DNA testing so far has not been able to definitively determine whether the viral particles are active or inactive.
Prater called the situation new and evolving but maintained that pasteurization and sterilization “have served public health well for more than 100 years.”
Suresh Kuchipudi, professor and chair of the department of infectious diseases and microbiology at the University of Pittsburgh School of Public Health, said studies on similar types of viruses have shown that pasteurization will inactivate the virus, although it does not eliminate it.
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Dawn O’Connell, assistant secretary for preparedness and response at the Department of Health and Human Services, emphasized that the risk to human health is low but that the federal government remains “vigilant and ready to keep the American people safe.”
Steve Lyle, a spokesman for the California Department of Food and Agriculture, who was not on the call, said in an email that the federal government is leading on this issue and the state has no additional response or information to share.
Government researchers are actively testing the virus found in milk samples in the laboratory to see whether it grows in cell cultures or embryonated chicken eggs. These tests will show whether the virus is active, said Jeanne Marrazzo, director of the National Institute of Allergy and Infectious Diseases.
Initial tests show that the virus is not alive.
They are also expanding surveillance and monitoring activities and suggest that more information will be released in the coming days.
In addition, they issued a federal order requiring laboratories to report testing of dairy cattle that test positive for bird flu or any form of influenza A, as well as all lactating dairy cattle moving between states. Mike Watson, director of the Animal and Plant Health Inspection Service, also said that any farm where bird flu positive cows are detected will need to undergo epidemiological investigation and movement tracing.
It was stated that the number of milk samples tested, where they were taken from and how many of the samples tested positive for the virus were not shared with journalists.
Nirav Shah, principal deputy administrator of the U.S. Centers for Disease Control and Prevention, said the agency has tested 23 people for the virus and is actively monitoring 44 people “who are considered exposed and at risk of infection.”
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So far, only one human case has been identified in the current outbreak, and this person has been reported to have only mild symptoms.
In other places where people were infected, the virus made people sicker and even became fatal. Between January 2003 and February 2024, there were 887 confirmed cases of human infection in 23 countries, according to the World Health Organization, which tracks the virus. Of these, 462 were fatal.
Although the current virus has not evolved the ability to further infect humans, researchers have noted some worrying mutations.
These include observations of the virus spreading between cows within the same herd (from cows to poultry) and movement of the virus between dairies in conjunction with cattle movements. It was also detected in cows that did not show clinical signs of the disease; This suggests that the disease moves unnoticed.
Separately, Watson, the USDA official, said on April 16 that a USDA microbiologist “detected a change” in a sample from McAllen, Kan., that indicated a mutation that would make it more transmissible among mammals. He said further analysis by the CDC showed “generally low risk.”
This story was first published in the Los Angeles Times.