US to start nationwide testing for H5N1 flu virus in milk supply
Ars Technica » Scientific Method 2024-12-06
On Friday, the US Department of Agriculture (USDA) announced that it would begin a nationwide testing program for the presence of the H5N1 flu virus, also known as the bird flu. Testing will focus on pre-pasteurized milk at dairy processing facilities (pasteurization inactivates the virus), but the order that's launching the program will require anybody involved with milk production before then to provide samples to the USDA on request. That includes "any entity responsible for a dairy farm, bulk milk transporter, bulk milk transfer station, or dairy processing facility."
The ultimate goal is to identify individual herds where the virus is circulating and use the agency's existing powers to do contact tracing and restrict the movement of cattle, with the ultimate goal of eliminating the virus from US herds.
A bovine disease vector
At the time of publication, the CDC had identified 58 cases of humans infected by the H5N1 flu virus, over half of them in California. All but two have come about due to contact with agriculture, either cattle (35 cases) or poultry (21). The virus's genetic material has appeared in the milk supply and, although pasteurization should eliminate any intact infectious virus, raw milk is notable for not undergoing pasteurization, which has led to at least one recall when the virus made its way into raw milk. And we know the virus can spread to other species if they drink milk from infected cows.