Scientific American Flash pasteurization destroyed H5N1 viral particles that were highly concentrated in raw milk, confirming that standard techniques can keep dairy products safe from bird flu.
Pasteurization—the process of using high heat to eliminate harmful microbes in foods—effectively kills the H5N1 avian influenza virus that is currently circulating in U.S. cattle. In a new study scientists at the Food and Drug Administration and U.S. Department of Agriculture pasteurized raw milk inoculated with high concentrations of the pathogen and found that the treatment inactivated it in all samples. The finding validates that this century-and-a-half-old technique can protect humans from infectious microbes. Both agencies recommend that people should not consume raw (unpasteurized) milk or raw milk products.
Concerns over the safety of dairy products have risen with reports of bird flu outbreaks at dairy cow farms in multiple states. As of June 28, there have been three human cases of avian flu in the U.S. this year, according to the Centers for Disease Control and Prevention. All identified cases were in dairy farm workers who had direct contact with infected cattle. The FDA and USDA had previously sampled retail dairy products that had been commercially pasteurized, about 20 percent of which contained H5N1 viral particles. None of the 297 samples—which came from 132 processing sites in 38 states and were collected from April 18 to 22—contained live infectious virus, however. (The results of the sampling study were initially released in May, prior to its upcoming publication in the Journal of Virology.)