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New Research Highlights the Importance of Milk Pasteurisation Amid Rising Bird Flu Concerns
Influenza viruses can remain infectious in refrigerated raw milk for up to five days, scientists have warned in a new study. The research, conducted by Stanford University, arrives at a critical moment when outbreaks of bird flu in dairy cattle are raising fears about the potential for a new pandemic.
“This work highlights the potential risk of avian influenza transmission through consumption of raw milk and the importance of milk pasteurisation,” said Alexandria Boehm, senior author of the study and a professor at the Stanford Doerr School of Sustainability and Stanford School of Engineering.
Proponents of raw milk argue that it retains beneficial nutrients, enzymes, and probiotics often reduced in pasteurised milk, claiming it can boost immune and gastrointestinal health. However, health experts warn that raw milk poses significant risks due to the presence of harmful germs.
The US Food and Drug Administration (FDA) has linked raw milk to over 200 outbreaks of illnesses. The agency stresses that pathogens like E. coli, Salmonella, and other dangerous microorganisms in unpasteurised milk present “serious” health risks, particularly for vulnerable groups, including children, pregnant women, the elderly, and those with weakened immune systems.
Influenza Virus Persistence in Raw Milk
The study, published in the journal Environmental Science and Technology Letters, examined the persistence of a human influenza virus strain, H1N1 PR8, in raw cow’s milk stored at standard refrigeration temperatures. Researchers discovered that the flu virus survived and remained infectious for up to five days.
“The persistence of infectious influenza virus in raw milk for days raises concerns about potential transmission pathways,” said co-lead author Mengyang Zhang, a postdoctoral scholar in civil and environmental engineering at Stanford. “The virus could contaminate surfaces and other environmental materials within dairy facilities, posing risks to animals and humans.”
Notably, while the infectious virus persisted for five days, flu virus RNA—genetic material from the virus that is not infectious—was detectable in raw milk for as long as 57 days. This finding highlights the durability of the virus’s genetic traces in milk.
Pasteurisation: A Critical Safety Measure
In a crucial comparison, the researchers found that pasteurisation effectively destroyed all infectious influenza viruses in milk and reduced the viral RNA by nearly 90 per cent, although traces of the RNA remained.
The study’s findings underscore the significance of pasteurisation as a critical public health measure. By heating milk to specific temperatures, pasteurisation eliminates infectious pathogens, ensuring safety for consumers.
Growing Concerns Amid Bird Flu Spread
The research emerges as bird flu outbreaks continue to impact livestock worldwide, raising concerns about zoonotic transmission—the transfer of viruses from animals to humans. The study’s authors emphasized the need for improved monitoring systems in dairy facilities to prevent potential viral contamination and spread.
“Our findings highlight the importance of stringent monitoring and control measures, particularly as avian influenza continues to spread among livestock,” the authors concluded.
With concerns about food safety and potential pandemic risks escalating, experts stress that pasteurised milk remains the safest option for consumers, protecting public health while minimising the risk of virus transmission.
Key Takeaway: While raw milk enthusiasts tout its perceived health benefits, the study provides a stark reminder of the risks associated with unpasteurised milk. Pasteurisation remains a critical safeguard, especially amid the rising threat of avian influenza.
