High H5N1 Influenza Levels Found in Mice Given Raw Milk from Infected Dairy Cows

https://www.niaid.nih.gov/news-events/high-h5n1-influenza-levels-found-mice-given-raw-milk-infected-dairy-cows?utm_campaign=+60723523&utm_content=&utm_medium=email&utm_source=govdelivery&utm_term= In NIAID-funded research results published today in the New England Journal of Medicine, mice administered raw milk samples from dairy cows infected with H5N1 influenza experienced high virus levels in their respiratory organs and lower virus levels in other vital organs. The results suggest that consumption of raw milk by animals poses a risk for H5N1 infection and raises questions about its potential risk in humans. Additionally, the researchers also tested to determine which temperatures and time intervals inactivate H5N1 virus in raw milk from dairy cows. Four milk samples with confirmed high H5N1 levels were tested at 63 degrees Celsius (145.4 degrees Fahrenheit) for 5, 10, 20 and 30 minutes, or at 72 degrees Celsius (161.6 degrees Fahrenheit) for 5, 10, 15, 20 and/or 30 seconds. Each of the time intervals at 63℃ successfully killed the virus. At 72℃, virus levels were diminished but not completely inactivated after 15 and 20 seconds. The authors emphasize, however, that their laboratory study was not identical to large-scale industrial pasteurization of raw milk and reflect experimental conditions that should be replicated with direct measurement of infected milk in commercial pasteurization equipment. In a separate experiment, the researchers stored raw milk infected with H5N1 at 4℃ (39.2 degrees Fahrenheit) for five weeks and found only a small decline in virus levels, suggesting that the virus in raw milk may remain infectious when maintained at refrigerated temperatures.