BACKGROUND: Cholera globally affects 1.3-4.0 million people and causes 21 000-143 000 deaths annually. In June 2017, a cluster of diarrhoeal illness occurred among participants of an international scientific conference at a hotel in Nairobi, Kenya. Culture confirmed Vibrio cholerae, serotype Ogawa. We investigated to assess magnitude, identify likely exposures and suggest control measures. METHODS: We carried out a retrospective cohort study utilizing a structured questionnaire administered by telephone, email and internet-based survey. We calculated food-specific attack rates, risk ratios and in a nested-case control analysis, performed logistic regression to identify exposures independently associated with the outbreak. RESULTS: We interviewed 249 out of 456 conference attendees (response rate=54.6%). Mean age of respondents was 37.8 years, ±8.3 years, 131 (52.6%) were male. Of all the respondents, 137 (55.0%) were cases. Median incubation time was 35 (11-59) hours. Eating chicken (adjusted OR 2.49, 95% CI, 1.22-5.06) and having eaten lunch on Tuesday (adjusted OR 2.34, 95% CI 1.09-5.05) were independently associated with illness; drinking soda was protective (adjusted OR 0.17, 95% CI 0.07-0.42). CONCLUSION: Point source outbreak, associated with chicken eaten at lunch on Tuesday 20th June 2017 occurred. We recommend better collaboration between the food and health sectors in food-borne outbreak investigations.
BACKGROUND: Cholera globally affects 1.3-4.0 million people and causes 21 000-143 000 deaths annually. In June 2017, a cluster of diarrhoeal illness occurred among participants of an international scientific conference at a hotel in Nairobi, Kenya. Culture confirmed Vibrio cholerae, serotype Ogawa. We investigated to assess magnitude, identify likely exposures and suggest control measures. METHODS: We carried out a retrospective cohort study utilizing a structured questionnaire administered by telephone, email and internet-based survey. We calculated food-specific attack rates, risk ratios and in a nested-case control analysis, performed logistic regression to identify exposures independently associated with the outbreak. RESULTS: We interviewed 249 out of 456 conference attendees (response rate=54.6%). Mean age of respondents was 37.8 years, ±8.3 years, 131 (52.6%) were male. Of all the respondents, 137 (55.0%) were cases. Median incubation time was 35 (11-59) hours. Eating chicken (adjusted OR 2.49, 95% CI, 1.22-5.06) and having eaten lunch on Tuesday (adjusted OR 2.34, 95% CI 1.09-5.05) were independently associated with illness; drinking soda was protective (adjusted OR 0.17, 95% CI 0.07-0.42). CONCLUSION: Point source outbreak, associated with chicken eaten at lunch on Tuesday 20th June 2017 occurred. We recommend better collaboration between the food and health sectors in food-borne outbreak investigations.