BACKGROUND : On 29 December 2021, public health officials reported a cluster of 45 cases with loose stools and vomiting after eating food at a feast organised for a funeral at Avarampatti village of Dindugal district, Tamil Nadu, India. Our objective was to identify source of the illness.
METHODS : We did a door-to-door survey to identify additional cases and collected information on demographic, symptom details and date & time of onset of symptoms. Further, we conducted a retrospective cohort study with a cohort comprising of all people who consumed food at the funeral and collected details about type of food consumed and illness. We calculated relative risk with 95% confidence interval for all food items served. We also collected blood samples from 5 patients and stool samples from 15 patients for laboratory analysis.
RESULTS : We identified a total of 94 cases in door-to-door survey. Their mean age was 37 years (SD:17.5) and 55% (n=52) cases were males. The characteristics of epi-curve indicated a point-source outbreak. Median incubation period was 11.5 hours. Spot-map showed sporadic distribution of cases. Attack rate was higher among individuals of 15-30-year age-group (18%). A total of 269 people partook in the feast. 8 food items were ordered from a catering service and one food item spinach (commonly called “Keerai”) was cooked locally and served for both lunch and dinner. Attack rate was 35% in males (n=52) and 36% in females (n=42) with (39.5%) were among 15-30 age group of people who consumed food. Of all food items served, incidence of gastrointestinal illness was higher among those who consumed Spinach (RR-3.1,95%CI:2.3-4.3). Other food items did not show association with gastrointestinal illness. Laboratory investigations did not detect presence of Salmonella, Shigella, Vibrio cholera and E. coli.
CONCLUSION : Gastro-intestinal illness might be due to Spinach (Keerai) served during the funeral feast. We recommend appropriate cooking and serving of food items, especially Spinach, to prevent such outbreaks.