Raw milk, which is marketed as a natural and healthier alternative to pasteurized dairy, may have hidden dangers, according to a new study. Research has found that influenza or flu virus can remain infectious in refrigerated raw milk for up to five days. The findings come as an outbreak of bird flu in dairy cattle has raised concerns about the possibility of a new pandemic. This study was conducted by Stanford University.
“This work highlights the potential risk of avian influenza transmission through raw milk consumption and the importance of milk pasteurization,” said senior author Alexandria Boehm, the Stanford Doerr School of Sustainability and the Richard and Rhoda Goldman Professor of Environmental Studies at Stanford. ” School of Engineering.
More than 14 million Americans consume raw milk annually. Unlike pasteurized milk, raw milk is not heated to kill potentially harmful pathogens. Proponents of raw milk claim that it releases more beneficial nutrients, enzymes and probiotics than pasteurized milk, and may boost immune and gastrointestinal health.
The Food and Drug Administration has blamed raw milk for the spread of more than 200 diseases, and – in conjunction with the Centers for Disease Control and Prevention – warns that germs in raw milk, such as E. coli and Salmonella, are particularly Pose “serious” health risks. For children, elderly, pregnant women and people with weak immune systems.
Researchers detected the persistence of human influenza virus strains in raw cow’s milk at normal refrigeration temperatures. The flu virus, called H1N1 PR8, survived in milk and remained infectious for up to five days.
“The persistence of infectious influenza virus in raw milk for several days raises concerns about potential transmission routes,” said study co-lead author Mengyang Zhang, a postdoctoral scholar in civil and environmental engineering. “The virus can contaminate surfaces and other environmental materials within dairy facilities, posing a risk to animals and humans.”
Additionally, researchers found that flu virus RNA – molecules that carry genetic information but are not considered a health threat – remained detectable in raw milk for at least 57 days. By comparison, pasteurization completely destroyed infectious influenza in milk and reduced the amount of viral RNA by about 90%, but did not completely eliminate the RNA. Although exposure to influenza virus RNA does not pose a health risk, RNA-based testing methods are often used to conduct environmental surveillance of pathogens such as influenza.
“The long-term persistence of viral RNA in both raw and pasteurized milk has implications for food safety assessment and environmental monitoring, particularly because many of the techniques used in environmental monitoring detect RNA,” said study co-leader said author and postdoctoral scholar Alessandro Zulli. Civil and Environmental Engineering.
The research evolved from an earlier project — funded by the Stanford Woods Institute for the Environmental Venture Projects program — that focused on human norovirus and the subfamily of viruses responsible for the Covid-19 pandemic.
In the US alone, the flu virus infects more than 40 million people and kills more than 50,000 every year. These types of viruses can spread from animals to humans, as in the case of swine flu, which caused 1.4 billion human infections globally in 2009–2010.
Although bird flu has not yet proven to be that dangerous for people, it can mutate and become dangerous. The recent detection of bird flu in cattle has raised questions about its possible transmission through milk and other dairy products.
According to the study authors, the study’s findings underscore the importance of improving surveillance systems, especially when bird flu is spreading among livestock.
This study complements earlier research involving many of the same researchers who pioneered the use of wastewater to detect avian influenza. That analysis highlighted commercial and industrial dairy waste as the primary source. By analyzing wastewater, public health officials can detect virus activity in nearby cattle populations.
“We never imagined that wastewater could be used to detect and respond to zoonotic pathogens circulating in the community,” Boehm said. “It has been amazing to see our work on wastewater detection across the United States and around the world.”
