Ohio State University Jun 15 2026 Just 10 viral particles of the H5N1 bird flu that caused hundreds of influenza outbreaks in U.S. dairy cattle can cause infection in cows, a new study shows. The research also hints at why the outbreaks have confounded scientists, farmers and livestock handlers hoping to contain and prevent the disease – an effort likely complicated by the fact that the virus has an affinity for cow mammary glands rather than airways. Tests for transmission among cows through