Table 1.

Main epidemiological findings for pond-centred cholera outbreaks, FETP, West Bengal, India, 2004-2008

Background information	No. (year)	1 (2004)	2 (2006)	3 (2007)	4 (2007)	5 (2008)
	Setting	Rural	Urban slum	Rural	Rural	Rural
	District	South 24 Paraganas	South 24 Paraganas	South 24 Paraganas	Howrah	Nadia
Magnitude and severity	No. of cases	55	56	32	63	71
	Rate per 1,000	42	121	51	22	77
	deaths/case fatality	2 (3.6%)	0 (0%)	1 (3.1%)	0 (0%)	0 (0%)
Descriptive epidemiology	Median age (years)	18	24	22	30	20
	% of females	50	55	50	54	59
	Duration (days)	11	6	11	15	13
	No. of modes on epidemic curve	1 (common source)	1 (point source)	1 (common source)	2 (common source)	1 (common source)
	No. of ponds	3	1	1	1	2
Analytical epidemiology methods		Case control	Retrospective cohort	Case control	Case control	Case control
Relative risk /odds ratio (95% CI)	Washing utensils	N/A	12 (4.8-31)	10 (7.0-13)	9.3 (2.8-31)	6 (2.3-15)
	Swallowing water	8.3 (2.4-35)	N/A	3.5 (1.2-10)	1.3 (0.6-2.8)	9.3 (3.3-26)
	Washing mouth	N/A	N/A	N/A	1.81 (0.9-3.8)	4.8 (1.8-13)
	Drinking-water	N/A	N/A	N/A	2.1 (0.9-4.7)	3.2 (1.3-8.2)
	Cooking with water	N/A	N/A	N/A	3.0 (1.3-7.1)	0.78 (0.4-1.6)

NA=Not available;

CI=Confidence interval;

FETP=Field Epidemiology Training Programme