Samples of pasteurized milk have tested positive for remnants of the bird flu virus, the U.S. Food and Drug Administration (FDA) announced. The agency emphasized that the detected material is inactivated and does not present any risk to consumers. The FDA continues to investigate the matter.
In a statement released on Tuesday, the FDA stated, “To date, we have seen nothing that would change our assessment that the commercial milk supply is safe.”
The announcement follows the detection of an avian influenza virus in dairy cows in at least eight states. This virus has been responsible for sickening millions of wild and commercial birds in recent years. According to the Agriculture Department (USDA), 33 herds have been affected so far.
The FDA has not disclosed the number of samples tested or their origin. However, officials indicated that the agency has been evaluating milk during processing and at grocery stores. Results of additional tests are anticipated “in the next few days to weeks.”
The FDA utilized the polymerase chain reaction (PCR) lab test, which can detect viral genetic material even after pasteurization or heat treatment has killed the live virus. Lee-Ann Jaykus, an emeritus food microbiologist and virologist at North Carolina State University, explained that “There is no evidence to date that this is infectious virus, and the FDA is following up on that.”
Previously, officials from the FDA and USDA stated that milk from affected cattle did not enter the commercial supply. Regulations mandate that milk entering interstate commerce be pasteurized, and sick animals’ milk is typically diverted and destroyed.
Due to the novelty of detecting the bird flu virus known as Type A H5N1 in dairy cattle, no studies have been completed on the effects of pasteurization on the virus. However, the FDA cited past research suggesting that pasteurization is likely to inactivate heat-sensitive viruses such as H5N1.
The agency has been evaluating milk from infected animals at various stages, including those in the processing system and on store shelves. It is working on completing a large, representative national sample to assess the extent of the findings.
Furthermore, the FDA is conducting egg inoculation tests to determine whether any positive findings indicate the presence of viable virus. Matt Herrick, a spokesperson for the International Dairy Foods Association, stated that pasteurization’s time and temperature regulations ensure the safety of the commercial U.S. milk supply. He emphasized that remnants of the virus “have zero impact on human health.”
The confirmation of the H5N1 virus in dairy cows in March followed reports of a mysterious illness affecting cows in Texas. Affected cows exhibited lethargy and reduced milk production. While the H5N1 virus can be deadly to commercial poultry, most infected cattle reportedly recover within two weeks.
To date, two individuals in the U.S. have contracted bird flu. A Texas dairy worker who had close contact with an infected cow recently developed a mild eye infection but has since recovered. In 2022, a prison inmate in a work program contracted the virus while killing infected birds at a Colorado poultry farm. He experienced only fatigue and has also recovered.
