Transmission of diarrhoea in two crowded areas with different sanitary facilities in Dhaka, Bangladesh.

To determine the importance of water-borne and water-washed transmission of diarrhoea we compared the degree of contamination of children's hands and drinking water with their diarrhoeal morbidity. Diarrhoeal incidence in 137 children aged 1-6 years was obtained through fortnightly home visits during the calendar year 1985. Bacterial contamination of hands and drinking water was assessed semi-quantitatively by direct contact using agar-coated slides incorporating a selective medium permitting growth of Enterobacteriaceae (Hygicult, Orion Diagnostica, Finland). Results were expressed as 2-day mean log of colony forming units per gram (cfu/g). Children were studied in two densely populated urban areas: 56 children in one area with latrines and tubewells and 81 children in the other without such facilities. Mean diarrhoea attack rates were lower in the better sanitary area (2.5 vs 3.2, P less than 0.05) as were mean log levels of water contamination (3.1 cfu/g vs 4.3 cfu/g, P less than 0.001). There was no significant correlation between water contamination and diarrhoeal incidence on an individual basis. However, in both areas diarrhoea incidence was significantly correlated with the degree of contamination of hands. After adjusting for age the risk of diarrhoea increased significantly for children with more contaminated hands in the unimproved area. This relationship strongly supports the promotion of handwashing as a method of controlling diarrhoeal diseases and, by implication, the greater importance of water quantity compared to quality.