Measurement of seasonal variations in endemic cholera in West Bengal.

This paper is a report on an attempt to study seasonal variations in endemic cholera in West Bengal by statistical analysis of monthly mortality records over a 21-year period. The annual death-rates have been calculated for each month in each district and the average of the seven lowest rates in each district is plotted diagrammatically to show the seasonal endemicity.BY THIS MEANS THREE GROUPS OF DISTRICTS ARE DISTINGUISHED: one of high, one of variable, and one of low or no endemicity. The statistical analysis suggests that cholera experience in West Bengal is not, as is sometimes contended, dependent on the intensity of infection in Calcutta.It is felt that the method described might to advantage be applied to other areas where cholera is endemic and would be helpful in selecting the most suitable times for carrying out control measures.