An educational intervention for altering water-sanitation behaviors to reduce childhood diarrhea in urban Bangladesh. I. Application of the case-control method for development of an intervention.

A case-control study was performed to develop an empirically based intervention for improving water-sanitation practices and rates of childhood diarrhea among families residing in urban Bangladesh. For three months fortnightly, histories of diarrhea were taken for all children under six years of age among 1,350 families to estimate age-specific rates of diarrhea in the population. A total of 247 randomly sampled families, termed sentinel families, were visited once during the study for prolonged observations of water-sanitation practices. Behaviors potentially affecting incidence of diarrhea were compared in a case group (n = 45), defined as sentinel families whose children had rates at least 1.7 times the rates expected for similarly aged children, and in a control group (n = 53), defined as sentinel families without any episodes of childhood diarrhea during the period of observation. Three practices differentiated the two groups: more control (82%) than case (53%) mothers who were observed to prepare food washed their hands before beginning the preparation (p less than 0.01); fewer control families (33%) than case families (80%) had ambulatory children who, when observed to defecate, did so in the family's living area (p less than 0.01); and fewer control (30%) than case (47%) families had children who were observed to place garbage or waste products in their mouth (p less than 0.10). Focus on these three empiric associations enabled the design of a community-specific educational intervention which is simple in construction and based upon naturally occurring, financially feasible, salutory practices.