A Troubling Study Unveils Raw Milk Risks

A groundbreaking new study has revealed alarming findings about the H5N1 bird flu virus, showing that it can remain infectious in raw milk for more than a day at room temperature and over a week when chilled. This has raised urgent red flags about the potential for zoonotic transmission—that is, from animals to humans—through unpasteurized dairy products.

Research Details and Findings

Published on the preprint server medRxiv on May 28, this comprehensive lab study was carried out by a team of scientists from the UK, who meticulously examined how the highly pathogenic H5N1 virus behaves in raw milk sourced from cows and sheep. The timing of these findings is particularly concerning, as cases of this virus have surged in U.S. dairy herds since late 2023.

The researchers reported remarkably high levels of the virus in milk from infected cows, prompting worries about the potential for human infections. They emphasized that while pasteurization effectively kills off influenza viruses, the risk remains high for those consuming unpasteurized milk or working in dairies.

The Rising Threat of H5N1 in U.S. Farms

Since the virus first made its way into U.S. dairy cattle, it has spread alarmingly across more than a thousand cattle herds. Additionally, various mammal species and numerous dairy workers have tested positive, including several individuals with no direct contact with infected animals.

How the Research Was Conducted

To understand how the virus could persist, researchers simulated real-world dairy conditions by incubating the virus in pasteurized cow's milk at both room temperature and a chill of 4°C (39.2°F). They also conducted tests on sheep’s milk using a laboratory strain of avian influenza, showcasing the extensive measures taken to explore this critical issue.

What This Means for Consumers

These unsettling findings serve as a stark reminder: the consumption of raw dairy products poses significant health risks. With H5N1 spreading in livestock, public health officials urge consumers to prioritize safety by opting for pasteurized dairy products. The implications are serious—understanding this threat is crucial for safeguarding both public health and the integrity of the dairy industry.