Missouri investigates more possible human-to-human H5N1 avian flu spread University of Minnesota Twin CitiesCDC A(H5N1) Bird Flu Response Update September 27, 2024 CDCFour Missouri healthcare workers develop symptoms after bird flu exposure BBC.comMore health-care workers in contact with Missouri bird flu patient report respiratory symptoms CNNPossible Cluster of Human Bird-Flu Infections Expands in Missouri The New York Times