An explosive outbreak of cholera in a shelter home for mentally retarded females, Howrah, West Bengal, India, 2010

Background: On 13th May 2010, a cluster of diarrhea cases was reported among female residents of a shelter home for mentally retarded, Per-bakshi village, Amta-II block in Howrah district, India. We investigated the outbreak to identify etiologic agent, source of infection and to propose recommendation.

Methods: We defined a suspected case of cholera as an acute onset of watery stools with or without vomiting in female residents of shelter home, from 1st May 2010. We collected stool specimen from case patients and water samples from all the drinking water sources in the shelter home for microbiological investigations. We collected demographic and clinical details of cases from hospital and home to describe the outbreak by time and person and conducted a retrospective cohort study to identify the source of infection.

Results: We identified 91cases (including 3 deaths) among 101 inmates (Attack rate: 90%, case fatality: 3%). Four of the five stool specimens tested positive for V. cholerae O1 ogawa. Water of pond connected tube-well had fecal coliforms. The shape of epidemic curve suggested a point source outbreak. Pond-connected tube well meant for domestic use was adjacent to the ground water tube well meant for drinking purpose. Among the 87 (86%) inmates included in the cohort study, consumption of pond connected tube-well was more likely to be associated with the illness (Adjusted odds ratio =25.7, 95% CI=2.7-236.4)] than those using ground water tube-wells.

Conclusions: The outbreak was associated with the accidental consumption of water from the pond-connected tube well. We recommended re-location of pond connected tube-well, color coding and disinfection of all ground water tube-wells.


Author (s): 

Subhransu S Datta, R. Ramachandran, M. V. Murhekar National Institute of Epidemiology, Indian Council of Medical Research, Chennai, India.

Presenter (s): 
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