The Food and Drug Administration (FDA) has identified genetic evidence of the H5N1 bird flu virus in pasteurized commercially purchased milk through testing. However, the testing method employed, polymerase chain reaction (PCR), cannot distinguish between live virus and fragments of viruses potentially inactivated by the pasteurization process. The agency is attempting to cultivate virus from the H5N1-positive milk samples, considered the gold standard test for determining viable virus presence.
Despite the detection, the FDA maintains that commercial, pasteurized milk remains safe for consumption, stating that the findings have not altered this assessment. The FDA’s statement offers assurances but lacks specific details regarding the extent of testing conducted. It does not specify the number of commercial samples tested, the markets from which they were collected, or the percentage of samples with positive PCR results for H5N1. Additionally, the statement does not provide information about the quantity of viral genetic material detected in the milk samples.
The FDA initiated this commercial survey to evaluate the federal-state milk safety system amidst the ongoing H5N1 bird flu outbreak affecting dairy cows in eight states. As of Monday, 33 herd outbreaks have been confirmed. The agency emphasizes that pasteurization is highly likely to inactivate H5N1, although no specific studies have examined the impact of pasteurization on H5N1 viruses. The FDA cites previous studies supporting the effectiveness of pasteurization in inactivating heat-sensitive viruses, including H5N1, in milk from cows and other species.
Ongoing testing of commercially available milk continues, including efforts to identify any potential variations between different dairy products like cream and whole milk.
