BACKGROUND: In July 2016, the New Hampshire (NH) Department of Health and Human Services investigated an outbreak of Shiga Toxin-Producing Escherichia coli(STEC). Fifteen cases were identified, including eight from a residential camp. Seven additional cases not associated with the camp were identified using pulsed field gel electrophoresis (PFGE).
METHODS: A case was defined as any individual with culture-confirmed STEC with illness onset after June 15, 2016 and indistinguishable PFGE patterns to the outbreak strain (Xbal: EXHX01.1107, Blnl: EXHA26.4626). Cases associated with the residential camp were interviewed using a camp-specific questionnaire, and cases not associated with the camp were interviewed using a standard enteric disease questionnaire. Environmental assessments of implicated food exposures were conducted to identify food service practices of concern and common food suppliers.
RESULTS: Fifteen cases were identified. Cases were residents of New Hampshire, California, Maine, Maryland, Massachusetts, New York, Vermont, and Canada. The most common symptoms among cases were diarrhea (100%), abdominal cramps (100%), and bloody diarrhea (87%). Five cases (33%) were hospitalized and one case developed hemolytic uremic syndrome. No cases died. Fourteen out of 15 food histories were obtained. Raw or undercooked ground beef exposure was documented in 87% of cases prior to onset of symptoms. Environmental assessment identified a common beef supplier in NH. USDA notified and a traceback investigation was initiated. USDA inspected the slaughter and processing facility associated with the beef and identified a single slaughter day as the possible source of contamination. Approximately 8,800 pounds of ground beef and other beef products were recalled as a result of the traceback. Two ground beef samples obtained from the camp both tested negative for STEC, but were not from the recalled lot.
CONCLUSIONS: Exposure to raw or undercooked ground beef from a common supplier was the source of this STEC outbreak. A multistate recall of ground beef and other beef products resulted in the cessation of the outbreak. In addition to assuring appropriate slaughter and processing procedures, consumers should ensure that all beef is cooked to an internal temperature of 160°F (71°C) using a meat thermometer, and that people preparing foods wash their hands frequently, particularly after working with raw food.