Uncooked milk, hailed by some as a pure and nutritious different to pasteurized dairy, could include hidden risks, in line with a brand new Stanford College examine. The analysis, printed December 12 in Environmental Science & Know-how Letters reveals that influenza or flu virus can stay infectious in refrigerated uncooked milk for as much as 5 days. The findings come at a time when outbreaks of hen flu in dairy cattle have raised issues concerning the potential for a brand new pandemic.
“This work highlights the potential danger of avian influenza transmission by way of consumption of uncooked milk and the significance of milk pasteurization,” mentioned examine senior writer Alexandria Boehm, the Richard and Rhoda Goldman Professor of Environmental Research within the Stanford Doerr College of Sustainability and the Stanford College of Engineering.
Greater than 14 million Individuals eat uncooked milk yearly. In contrast to pasteurized milk, uncooked milk isn’t heated to kill doubtlessly dangerous pathogens. Proponents of uncooked milk declare that it leaves extra useful vitamins, enzymes, and probiotics than in pasteurized milk, and may enhance immune and gastrointestinal well being.
The Meals and Drug Administration has tied uncooked milk to over 200 outbreaks of diseases, and — along with the Facilities for Illness Management and Prevention — warns that germs, such E. coli and Salmonella, in uncooked milk current “critical” well being dangers, particularly for youngsters, the aged, pregnant girls, and folks with weakened immune programs.
The science behind the chance
The researchers explored the persistence of a pressure of human influenza virus in uncooked cow’s milk at typical refrigeration temperatures. The flu virus, known as H1N1 PR8, survived and remained infectious within the milk for as much as 5 days.
“The persistence of infectious influenza virus in uncooked milk for days raises issues about potential transmission pathways,” mentioned examine co-lead writer Mengyang Zhang, a postdoctoral scholar in civil and environmental engineering. “The virus might contaminate surfaces and different environmental supplies inside dairy services, posing dangers to animals and people.”
Moreover, the researchers discovered that flu virus RNA — molecules that carry genetic info however usually are not thought-about a well being danger — remained detectable within the uncooked milk for not less than 57 days. By comparability, pasteurization utterly destroyed infectious influenza within the milk and lowered the quantity of viral RNA by nearly 90%, however did not get rid of the RNA completely. Though publicity to influenza virus RNA doesn’t pose a well being danger, RNA-based testing strategies are sometimes used to conduct environmental surveillance of pathogens like influenza.
“The extended persistence of viral RNA in each uncooked and pasteurized milk has implications for meals security assessments and environmental surveillance, significantly as a result of lots of the methods utilized in environmental surveillance detect RNA,” mentioned examine co-lead writer Alessandro Zulli, a postdoctoral scholar in civil and environmental engineering.
The analysis grew out of an earlier undertaking — funded by the Stanford Woods Institute for the Atmosphere’s Environmental Enterprise Tasks program — centered on human norovirus and the subfamily of viruses answerable for the COVID-19 pandemic.
Why it issues now
Within the U.S. alone, flu viruses infect greater than 40 million individuals and kill greater than 50,000 yearly. These kind of viruses can unfold from animals to people, as within the case of swine flu, which led to as many as 1.4 billion human infections globally in 2009-2010.
Though hen flu has not confirmed as harmful to individuals but, it might mutate to turn into so. Latest detection of hen flu in cattle has raised questions on its potential transmission by way of milk and different dairy merchandise.
The examine’s findings underscore the significance of bettering monitoring programs, significantly as hen flu continues to unfold amongst livestock, in line with the examine’s authors.
The examine enhances earlier analysis involving a number of of the identical researchers that pioneered using wastewater for detection of avian influenza. That evaluation revealed business and industrial dairy waste as major sources. By analyzing wastewater, public well being officers might detect virus exercise in close by cattle populations.
“We by no means thought that wastewater might be used to detect and reply to zoonotic pathogens circulating locally,” Boehm mentioned. “It has been wonderful to look at our work on detection in wastewater scaled throughout the USA and the world.”
Acknowledgments
Boehm can also be professor of Oceans within the Stanford Doerr College of Sustainability and a senior fellow on the Stanford Woods Institute for the Atmosphere.
The examine’s coauthors additionally embrace Catherine Blish, the George E. and Lucy Becker Professor in Medication on the Stanford College of Medication; and Sehee Jong, a analysis assistant in civil and environmental engineering.
The examine was funded by the Stanford Woods Institute for the Atmosphere and by the Sergey Brin Household Basis.
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