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In an unexpected turn of events, remnants of the H5N1 avian flu virus were detected in roughly 20% of US retail milk samples, according to recent announcements from the US Food and Drug Administration (FDA). These findings have raised new questions about the risk of infection through the nation’s milk supply, as detailed by top officials in an interagency briefing.
The FDA’s survey, the most comprehensive of its kind to date, revealed higher concentrations of the virus’ remnants in areas where outbreaks among dairy cattle had previously occurred. Acting director of the FDA Center for Food Safety and Applied Nutrition (CFSAN), Donald Prater, DVM, presented these findings at a scientific symposium on H5N1 hosted by the Association of State and Territorial Health Officials (ASTHO).
Although the testing detected viral fragments, scientists have yet to find any viable (potentially infectious) virus in the positive samples. Prater reassured the public that this does not change the FDA’s stance on the safety of the nation’s milk supply. Despite the reassurances, the FDA is faced with a backlog of research, seeking to understand the risk of human infection from oral consumption and providing proof that pasteurization methods can effectively inactivate H5N1.
Rosemary Sifford, DVM, of the US Department of Agriculture (USDA), confirmed that the agency is continuously sharing genetic sequences with public databases to maintain transparency. Investigations to understand how the virus is moving and transmitting among cattle on farms is ongoing.
Scientists are also evaluating virus presence in other species such as feral pigs and conducting regular influenza surveillance on commercial pigs.
Meanwhile, the Centers for Disease Control and Prevention (CDC) is examining the risk of infection from milk exposure and the conditions that may elevate these risks, such as aerosolization.
The CDC also uses an Influenza Risk Assessment Tool (IRAT) to evaluate the virus and prioritize resources. The assessment tool, according to Dr. Vivien Duggan, who leads the CDC’s Influenza Division, grades the virus based on 10 data criteria to determine its potential threat.
Government countermeasure experts, addressing concerns around the antiviral supply chain, have confirmed that they do not foresee any issues in this area.
David Boucher, Ph.D., director of infectious disease preparedness and response at the Department of Health and Human Services Administration for Strategic Preparedness, noted that the first wave of vaccine production could yield several hundreds of thousands of doses, with a second tranche potentially hitting 10 million doses.
While experts discuss safety precautions and continue investigations into this unprecedented situation, the FDA and USDA maintain based on current data that the commercial milk supply remains safe for consumption.
Information Box:
Avian Influenza or ‘Bird Flu’ refers to influenza caused by viruses adapted to birds but can affect other species including humans. The H5N1 strain is highly pathogenic and can be deadly to birds and mammals.
Viruses can be carried by wild birds and transmitted to domestic poultry and other bird species. Human infection, while sporadic, has occurred.
At present, it’s crucial to understand how H5N1 is transmitted among cattle and whether the milk from these animals presents any risk to humans.
References:
Reference 1: University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP)
Reference 2: U.S. Food and Drug Administration (FDA) Center for Food Safety and Applied Nutrition (CFSAN)
Reference 3: Centers for Disease Control and Prevention (CDC)