Mice experienced high levels of bird flu after being given raw milk, according to a study published Friday amid warnings from public health officials to refrain from drinking the unpasteurized dairy product.
Researchers from the University of Wisconsin-Madison and the Texas A&M Veterinary Medical Diagnostic Laboratory gave droplets of raw milk from cows that were infected to five mice. On the first day they showed signs of sickness, according to the study published in the New England Journal of Medicine.
The researchers found high levels of the virus in the trachea, nasal passages and lungs of the mice, the study said. Lower amounts were found in other organs. They also found that the level of bird flu dipped when the milk was stored at a lower refrigerator temperature, but the authors warned the study settings were not identical to large-scale industrial pasteurization of raw milk.
This week, a farmworker in Michigan became the second person confirmed to be infected by bird flu in the U.S. Both people had mild symptoms and have since recovered.
Bird flu was first noticed in cows two months ago, and it has been detected in 51 herds and in nine states since.
But scientists and public health officials say the U.S. is not conducting enough testing to capture the full spectrum of the spread.
Bird flu has caused deadly infections around the world. The virus has circulated in at least 23 countries since 2003, causing around 900 cases in humans, usually among people who get close to birds that are infected.