U.S – One in five samples of retail milk collected by the U.S. Food and Drug Administration’s Center for Food Safety and Applied Nutrition (FDA’s CFSAN) has tested positive for genetic material of Highly Pathogenic Avian Influenza (HPAI) H5N1, commonly known as “bird flu.”

Donald Prater, D.V.M., Acting Director of the FDA’s CFSAN, revealed this during a recent virtual scientific symposium hosted by the U.S. Association of State and Territorial Health Officials (ASTHO).

While further testing is necessary to determine if intact HPAI H5N1 is present in retail milk and whether it remains infectious, Dr. Prater emphasized the need for caution. The samples with the highest concentrations of HPAI H5N1 particles were traced back to regions where cases of the virus have been confirmed in dairy cattle.

Despite these findings, the FDA maintains confidence in the safety of the U.S. milk supply, reports Food Safety Magazine.

Nearly 99 percent of commercial milk in the U.S. is produced under the Grade “A” milk program, adhering to rigorous safety standards outlined in the Pasteurized Milk Ordinance (PMO). This program ensures the implementation of controls, including pasteurization, to mitigate microbial contamination risks.

Acknowledging scientific data gaps surrounding HPAI and bovine milk, Dr. Prater outlined ongoing collaborative efforts between the FDA and the U.S. Department of Agriculture (USDA) to address these concerns. Key research focuses include pasteurization studies, viral load assessments, and retail food sample analysis to better understand the food safety implications of HPAI H5N1.

Effectiveness of pasteurization in inactivating avian influenza

In a recent update, the FDA shared additional results from its national commercial milk sampling study, conducted in collaboration with the U.S. Department of Agriculture (USDA). This ongoing study, comprising 297 retail dairy samples, aimed to assess the presence of Highly Pathogenic Avian Influenza (HPAI) in dairy products.

Preliminary results from egg inoculation tests on a subset of 201 qPCR-positive retail dairy samples, including cottage cheese, sour cream, and fluid milk, have shown that pasteurization effectively inactivates HPAI.

Notably, no live infectious virus was detected in these samples, reaffirming the FDA’s assertion regarding the safety of the commercial milk supply.

In addition to retail dairy products, the FDA also examined samples of powdered infant formula and powdered milk products marketed as toddler formula. All qPCR results from formula testing returned negative, indicating no presence of HPAI viral fragments or virus in powdered formula products, eliminating the need for further testing on these samples.

FDA’s vigilance extends to samples of pooled raw milk destined for pasteurization and commercial processing. This ongoing testing aims to characterize potential virus levels encountered during pasteurization, further informing efforts to validate the efficacy of pasteurization in eliminating HPAI.

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