A recent Stanford University study has raised concerns about the safety of raw milk, demonstrating that the influenza virus can survive and be infectious in refrigerated raw milk for up to five days. The findings, published on December 12 in Environmental Science & Technology Letters, are particularly noteworthy in light of recent bird flu outbreaks in dairy cattle, which have raised concerns about potential pandemic pathways.

The study highlights the critical significance of milk pasteurisation, a technique that eliminates hazardous germs. "This work highlights the potential risk of avian influenza transmission through raw milk consumption and the importance of milk pasteurisation," said senior author Alexandria Boehm, a professor at Stanford's Doerr School of Sustainability.

The Risks of Consuming Raw Milk

Marketers frequently market raw milk for its purported nutritional benefits, and over 14 million Americans continue to enjoy it. Proponents argue that raw milk maintains more beneficial enzymes, minerals, and probiotics than pasteurised milk. However, health officials such as the FDA and CDC have long advised against its intake, citing major health hazards, particularly for vulnerable groups such as children, pregnant women, and the elderly.

The FDA connects approximately 200 sickness outbreaks to raw milk intake, with pathogens such as E. coli and Salmonella posing major risks. This new study adds influenza to the list of potential dangers, raising questions about raw milk safety.

Scientific Results: Virus persistence in raw milk

Stanford researchers investigated the durability of the H1N1 influenza virus, a common flu strain, in raw cow's milk kept at refrigeration temperatures. The findings were surprising. "The persistence of infectious influenza virus in raw milk for days raises concerns about potential transmission pathways," said Mengyang Zhang, study co-leader and postdoctoral scholar.

The findings shed light on the persistence and mitigation of the H1N1 flu virus in raw milk. The study discovered that the virus maintained its infectiousness in raw milk refrigerated for up to five days. Viral RNA remained in milk for up to 57 days even after the virus lost its ability to infect, indicating the long-term presence of genetic material despite the virus's non-infectivity. Pasteurization, on the other hand, proved to be quite successful in completely neutralizing the presence of the infectious virus.  Furthermore, the pasteurisation method reduced viral RNA concentration by 90%, highlighting its crucial function in both virus elimination and minimising the potential transmission risk associated with raw milk consumption. These findings emphasise the relevance of pasteurisation as a public health strategy, as it provides a dependable approach for minimising the risk of influenza transmission through milk.

Despite not directly posing a health risk, environmental monitoring widely uses viral RNA to identify pathogen activity. "The prolonged persistence of viral RNA in both raw and pasteurised milk has implications for food safety assessments," said co-lead author Alessandro Zulli, a postdoctoral researcher.

Rising Concerns During Bird Flu Outbreaks

The study's timing is significant because avian flu continues to spread among dairy animals. Although bird flu has not yet presented a serious risk to people, its ability to mutate is a global concern. Over 40 million flu illnesses and 50,000 deaths occur in the United States each year, and zoonotic viruses such as swine flu have shown how pathogens can leap from animals to humans, creating huge epidemics.

The findings highlight the importance of strengthening surveillance techniques to detect viral activity in dairy environments. Recent breakthroughs include using wastewater analysis to detect avian influenza in cow populations. "We never thought that wastewater could be used to detect and respond to zoonotic pathogens circulating in the community," according to Boehm.

Public health takeaways

The findings convey a strong warning about the dangers of raw milk consumption, especially in light of rising health issues. Pasteurization remains the most effective method of protecting against viruses and dangerous bacteria.  The study also emphasizes the importance of improved environmental monitoring systems for detecting new infections early.

As avian influenza spreads and the risk of transmission increases, the research provides a timely warning. Consumers, dairy farmers, and public health officials must prioritize safety measures to minimize hazards and ensure that dairy products are safe for consumption.

The study builds on prior efforts by Stanford researchers to establish novel surveillance systems for detecting zoonotic infections, such as wastewater analysis. We cannot overstate the importance of this research in safeguarding global health, given the ongoing concerns about pandemic dangers.