Bird Flu can survive in raw milk for up to a week or longer

A new study by UK researchers has found that the H5N1 bird flu virus can stay infectious in raw milk for extended periods—lasting more than 24 hours at room temperature and over a week when refrigerated. While the research is still awaiting peer review, it underscores the potential risks tied to unpasteurized dairy products.

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The study, currently available on the preprint server medRxiv, looked at how long the virus can remain active in both cow and sheep milk under typical dairy storage conditions. Scientists simulated environments ranging from ambient room temperatures to cold storage, using both naturally infected cow milk and lab-controlled sheep milk samples.

The findings were striking: infected cow milk contained high levels of the virus, prompting the researchers to warn of possible transmission to humans, especially through direct handling or consumption of raw dairy.

Importantly, the scientists emphasized that standard pasteurization methods are highly effective at eliminating the virus. However, the continued popularity of raw milk in some circles, and the risk faced by farm and dairy workers, has raised public health concerns.

The researchers described their findings as a “worst-case scenario,” meant to show how long the virus might survive under specific conditions, rather than what typically occurs. Still, they urged caution and recommended continued vigilance to prevent animal-to-human transmission.

Since H5N1's arrival in North America in late 2021, it has wreaked havoc on poultry and dairy farms, contributing to major losses and surging egg prices. The U.S. Department of Agriculture reports that more than 12,000 birds have tested positive for the virus since the outbreak began.

As the situation develops, health authorities continue to monitor the virus’s spread and its potential implications for food safety and public health.