One of the main viruses that cause seasonal influenza can remain infectious in raw milk for days after it leaves a warm body, leading to avian influenza or “avian influenza,” according to a new experiment from Stanford University. Concerns have been raised about the potential for widespread use of the virus.
When researchers infected batches of raw milk with the H1N1 virus, a subtype of influenza A virus, and stored it at 4°C (about 39°F), a relatively standard household refrigeration temperature, they found that the pathogen It was found that it takes 2.3 days for a person to become infected. Reaching a 99% reduction in infectivity.
Remarkably, a small proportion of the virus particles remained infectious for up to five days. The recommended shelf life for refrigerated raw milk is five to seven days, meaning that even under ideal circumstances, milk containing viruses can transmit influenza to consumers.
Thankfully, pasteurization solved the threat. When researchers heated infected milk at 63°C for 30 minutes, they were able to inactivate the infectious influenza A virus.
“This study highlights the potential risk of avian influenza infection from raw milk consumption and the importance of pasteurizing milk.” say Alexandria Boehm, an environmental engineer from Stanford.
Boehm and his colleagues said they couldn’t find any other studies that looked at how long the virus can remain infectious in raw milk. It’s their first time and it happens at a critical time.
For the first time in the world, an outbreak of highly pathogenic avian influenza (HPAI) in the United States officially spread from birds to cattle, with hundreds of dairy farms across the United States infected with the H5N1 virus.
These results from Stanford University support the idea that pasteurization protects the public from influenza-infected milk, as H1N1 viruses are often used as a surrogate for H5N1 viruses in research.
Although this particular avian influenza strain has not yet been observed to be transmitted from human to human, it is possible that it can be transmitted from animals to humans. initial research Milk suggests the possibility of human infection.
Just a few weeks ago, public health officials in California detected the H5N1 virus. in raw milk That’s what was being sold. All products were recalled due to concerns about infecting consumers.
At present, it appears that the H5N1 virus can enter the mammary glands of cows and infect dairy farm workers who handle raw milk and milking machines. Some people are tame dairy farm cats There have been cases of people dying from drinking infected raw milk.
“The persistence of influenza virus in raw milk is concerning because raw milk consumption remains high in the United States due to cultural factors and some common misconceptions,” the authors said. There is. write.
“Some of these misconceptions include the idea that raw milk treats lactose intolerance and asthma, strengthens the immune system, and is more nutritious than pasteurized milk.”
None of these arguments Ultimately, the evidence supports that the risks of drinking raw milk are extremely dangerous and can even be fatal.
about 4 percent of Americans drink raw milk at least once a year, but even with such a small population directly at risk, the threat to public health still exists. The longer the HPAI virus spends in humans, the more it has a chance to learn its terrain and potentially mutate to become more infectious to our species in the future.
So far, U.S. dairy workers have only had mild symptoms when they have fallen ill, but historically H5N1 outbreaks among humans have been deadly. It remains at about 50%.
Even in the absence of bird flu, health officials warn that drinking unpasteurized milk can expose consumers to the pathogen.etc. listeria monocytogenes, Salmonella, campylobacterand E. coli.
Today, this health advice is more important than ever.
This study Environmental science and technology letter.
