HomeThe U.S. hasn’t seen a human bird flu case in 3 months. Experts are wondering why – PBS The U.S. hasn’t seen a human bird flu case in 3 months. Experts are wondering why – PBSCanada The U.S. hasn’t seen a human bird flu case in 3 months. Experts are wondering why PBS The US hasn’t seen a human bird flu case in 3 months. Experts are wondering why Medical Xpress