On 10 March 2010, an outbreak of diarrhoeal 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. A suspected case of cholera was defined as having
653 loose watery stools in a 24-hour period and searched for
case-patients in the workers\u2019 colony. The outbreak was described
by time, place, and person, and a case-control study was conducted to
identify the source of infection. Rectal swabs were collected from the
hospitalized case-patients, and the local water-supply system was
assessed. In total, 197 case-patients were identified among 5,910
residents of the workers\u2019 colony (attack rate 3.33%). Fifteen of
24 stool samples were positive for Vibrio cholerae O1. The outbreak
started on 7 March, peaked on 11 March, and ended on 16 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).
An outbreak of cholera occurred among workers of the jute mill due to
contamination of the drinking-water reservoir. It occurred within a few
days of re-opening of the mill after the workers\u2019 strike. Health
authorities need to enforce disinfection of drinking-water and
regularly test its bacteriological quality, particularly before
re-opening of the mill after the strike