BACKGROUND: On January 16, 2016, a citizen reported gastrointestinal illness among dinner theatre attendees to the Kansas Department of Health and Environment (KDHE). An investigation was initiated by KDHE and the Johnson County Department of Health and Environment to determine the cause of illness and implement control measures.
METHODS: Theatre attendees were interviewed with an outbreak-specific questionnaire by telephone or self-administered online survey. Stool specimens were tested at the Kansas Health and Environmental Laboratories, the Wisconsin State Laboratory of Hygiene, and the Minnesota Department of Health Public Health Laboratory. Environmental assessments were conducted by the Kansas Department of Agriculture on January 20, January 29, and April 5. Among theatre attendees from January 14—31, a retrospective cohort study evaluated persons meeting norovirus case definition (diarrhea or vomiting within 12–72 hours of attendance), and a nested case-control study evaluated persons reporting illness compatible with Clostridium perfringens (diarrhea within 6–24 hours of attendance).
RESULTS: Questionnaires were completed by 2,117 persons; 1,743 attended the theatre January 14—31. Seven stool specimens were tested; 5 (71%) were PCR-positive for norovirus Kawasaki 2014 GII.17, and 1 was positive for Clostridium perfringens enterotoxin type A and culture-confirmed. No pathogens were identified in the remaining specimen. Retrospective cohort analysis for norovirus included 1,567 persons of whom 621 (40%) were ill. Bread (OR=1.2, 95%CI: 1.1-1.5), salad (OR=2.5, 95%CI: 1.6-4.0), and salad ingredients jicama (OR=1.9, 95%CI: 1.5-2.4) and ranch dressing (OR=1.2, 95%CI: 1.0-1.3) were significantly associated with illness, as was eating food from the right-side buffet (OR=1.2, 95%CI: 1.1-1.4). Nested case-control analysis for Clostridium perfringens included 988 persons of whom 55 (6%) were ill. Eating burnt ends (OR=2.6, 95%CI: 1.0-6.8) and poppy seed dressing (OR=2.7, 95%CI: 1.2-6.2) were significantly associated with illness. Environmental assessments identified violations including bare-hand contact with ready-to-eat foods. Employee health checks were implemented. A cleaning company was hired January 29 to disinfect the facility when transmission continued following the norovirus clean-up procedure conducted by theatre employees January 22.
CONCLUSIONS: This outbreak marks the first identified outbreak of norovirus Kawasaki 2014 GII.17 in Kansas. Additionally, a subset of individuals with Clostridium perfringens was identified through epidemiological and laboratory investigation. Using an online questionnaire enhanced our ability to reach a large number of patrons while minimizing staff time required to conduct interviews. Educating employees on illness prevention and implementing the norovirus clean-up procedure reduced the spread of illness, and professional disinfection appeared effective in stopping transmission.