Cholera outbreak in Kamarhati municipality of West Bengal: Secondary data analysis of a rapid epidemic response

Abstract

Introduction: In September, 2021, an outbreak of acute diarrhoeal disease affected different wards of Kamarhati municipality of West Bengal. An epidemic investigation was conducted with the objective of identifying the time, place and person distribution of the epidemic. Methods: In this institution based cross-sectional study, an epidemic response team of College of Medicine and Sagore Dutta Hospital (CoMSDH) visited the patients admitted in the infectious diseases ward of the institute and enquired them using a pre-designed proforma. Stools samples were collected and sent for analysis to National Institute of Cholera and Enteric Diseases (NICED), West Bengal. The team also visited the affected wards and collected water samples for laboratory investigations. Collected data were collated in Google sheets and requisite analyses were done in Google sheet, online spreadsheet software. Spatial distributions of cases were shown using QGIS v2.38.Results: 208 patients admitted in infectious diseases ward of CoMSDH, Kamarhati, Kolkata in between 2nd - 13th September, 2021 were interviewed. The epidemic curve showed a rapid rise on 07th September, 2021 (57 cases) followed by a gradual fall over next 5 days. Majority of cases were clustered in Ward 1,2 and 3 of Kamarhati municipality. The attack rate was highest among the geriatric age group (≥60 years) followed by 19-60 years age group. Abdominal Pain (35.71%) and vomiting (28.57%) were commonly associated symptoms. Majority of the respondents (172, 87.76%) used intermittent tap water supply from local municipalities, followed by purchased mineral water (20, 10.20%) and water from Tala tank (4, 2.04%) for their drinking purpose. Stool and water samples revealed the presence of Vibrio Cholerae, O139 ogawa serotype. Conclusion:On the basis of the interim analysis, health education was initiated on the domestic treatment of water by boiling or using chlorine solution. Additionally, steps were taken for water treatment at the water treatment plants. This assisted in controlling the outbreak.