The Centers for Disease Control and Prevention (CDC), several states, and the U.S. Food and Drug Administration are investigating a multistate outbreak of Shiga toxin-producing E. coli O157:H7 infections (STEC O157:H7) in 13 states. Seventeen illnesses have been reported from California (3), Connecticut (2), Illinois (1), Indiana (1), Michigan (1), Nebraska (1), New Hampshire (2), New York (1), Ohio (1), Pennsylvania (1), Virginia (1), Vermont (1) and Washington (1). Illnesses started on dates from Nov. 15 through Dec. 8, 2017. The Public Health Agency of Canada also is investigating an outbreak of STEC O157:H7 infections in several provinces.
The CDC is performing whole genome sequencing on samples of bacteria making people sick in the United States to give us information about whether these illnesses are related to the illnesses in Canada. Preliminary results show that the type of E. coli making people sick in both countries is closely related genetically, meaning the ill people are more likely to share a common source of infection.
The Public Health Agency of Canada has identified romaine lettuce as the source of the outbreak in Canada. In the United States, state and local public health officials are interviewing sick people to determine what they ate in the week before their illness started. The CDC is still collecting information to determine whether there is a food item in common among sick people, including leafy greens and romaine.
Because it has not identified a source of the infections, the CDC is unable to recommend whether U.S. residents should avoid a particular food at this time.