Severe cholera outbreak following floods in a northern district of West Bengal

Abstract

Background & objectives: An explosive epidemic of cholera in the district of Malda in the state of West Bengal, was induced by devastating floods resulting from overflowing of the two main rivers of the district, at the end of July 1998, affecting 15 blocks and 2 municipalities. Diarrhoeal outbreak occurred around the middle of August after receding of the flood waters. Within two weeks of its onset, the outbreak spread throughout the district. An investigation was conducted to understand the epidemiological characteristics, identify the etiological agent, rationalise clinical management and suggest control measures.

Methods: The team visited the Block Primary Health Centres, surrounding the affected villages and also the district hospital. Morbidity and mortality data were collected and 88 patients were interviewed and examined clinically. Epidemiological and clinical observations were recorded. Rectal swabs were collected from both hospitalised and domiciliary cases.

Results: During the period between August and October 1998, 16,590 cases were reported with 276 deaths (case fatality rate of 1.7%). Twenty one of 29 (72%) rectal swabs were positive for Vibrio cholerae O1, biotype ElTor, serotype Ogawa. All the strains were sensitive to tetracycline, norfloxacilin, ciprofloxacilin, gentamycin, chloramphenicol but resistant to furazolidine, co-trimoxazole, nalidixic acid, streptomycin and ampicilin.

Interpretation & conclusions: Observations of the present study identified the epidemiological and clinical deficiencies in the management of the outbreak and recommendations were elaborated for its effective control.