Outbreak of Cholera among Workers of a Jute Mill in Kolkata, West Bengal, India

Background: On 10th March 2010, an outbreak of diarrheal disease was reported among workers of a jute mill in Kolkata, West Bengal, India. The cluster was investigated to identify the agent (s) and the source of infection and make recommendations.

Method: We defined a suspected case of cholera as occurrence of > 3 loose watery stools in a 24-hour period and searched for case-patients in workers’ colony. We described the outbreak by time, place and person. We conducted a case-control study among the mill workers to identify the source of infection. We also collected rectal swabs from the hospitalized case-patients, and assessed the local water-supply system.

Results: We identified 197 case-patients among 5,910 residents of workers’ colony (attack rate: 3.3%). Fifteen of 24 stool samples were positive for V. cholerae O1. The outbreak started on 7th March, peaked on 11th and ended on 16th March’2010. Compared to 120 controls, 60 cases did not differ in terms of age and socioeconomic status. Drinking-water from the reservoir within the mill premises was associated with an increased risk of illness [Odds ratio: 26.7, 95% confidence interval (CI): 11.4 – 62.6] and accounted for most cases (population attributable risk percentage = 82%, 95% CI = 70.8-92.9).

Conclusion: An outbreak of cholera occurred among workers of the jute mill due to contamination of the drinking-water reservoir. The outbreak occurred within a few days of re-opening of the mill after workers’ strike. Health authorities need to enforce disinfection of drinking-water and regularly test its bacteriological quality, particular before re-opening of the mill after the strike. 

Author (s): 

Prakash Mridha1, AK Biswas2, R. Ramakrishnan1, MV Murhekar1. 1 Field Epidemiology Training Programme (FETP), National Institute of Epidemiology, Chennai, India 2 Strategic Planning & Sector Reform Cell, Government of West Bengal, Department of Healt

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