The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) are investigating a multistate outbreak of Shiga toxin-producing E. coli O157:H7 infections (STEC O157:H7) in 15 states. States affected by the outbreak include California, Connecticut, Illinois, Indiana, Maryland, Michigan, Nebraska, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Virginia, Vermont, and Washington. The illnesses occurred between November 15 through December 12, 2017. Health authorities believe that the likely source of the outbreak appears to be leafy greens, but health officials have not identified a specific type of leafy greens that sick people ate in common. Learn more here.