Context: Washing hands with soap prevents diarrhea, but children at the highest risk of death from diarrhea are younger than 1 year, too young to wash their own hands. Previous studies lacked sufficient power to assess the impact of household handwashing on diarrhea in infants.
Objective: To evaluate the effect of promoting household handwashing with soap among children at the highest risk of death from diarrhea.
Design, setting, and participants: A cluster randomized controlled trial of 36 low-income neighborhoods in urban squatter settlements in Karachi, Pakistan. Field workers visited participating households at least weekly from April 15, 2002, to April 5, 2003. Eligible households located in the study area had at least 2 children younger than 15 years, at least 1 of whom was younger than 5 years.
Interventions: Weekly visits in 25 neighborhoods to promote handwashing with soap after defecation and before preparing food, eating, and feeding a child. Within intervention neighborhoods, 300 households (1523 children) received a regular supply of antibacterial soap and 300 households (1640 children) received plain soap. Eleven neighborhoods (306 households and 1528 children) comprised the control group.
Main outcome measure: Incidence density of diarrhea among children, defined as the number of diarrheal episodes per 100 person-weeks of observation.
Results: Children younger than 15 years living in households that received handwashing promotion and plain soap had a 53% lower incidence of diarrhea (95% confidence interval [CI], -65% to -41%) compared with children living in control neighborhoods. Infants living in households that received handwashing promotion and plain soap had 39% fewer days with diarrhea (95% CI, -61% to -16%) vs infants living in control neighborhoods. Severely malnourished children (weight for age z score, <-3.0) younger than 5 years living in households that received handwashing promotion and plain soap had 42% fewer days with diarrhea (95% CI, -69% to -16%) vs severely malnourished children in the control group. Similar reductions in diarrhea were observed among children living in households receiving antibacterial soap.
Conclusion: In a setting in which diarrhea is a leading cause of child death, improvement in handwashing in the household reduced the incidence of diarrhea among children at high risk of death from diarrhea.