Setting Research Priorities to Reduce Mortality and Morbidity of Childhood Diarrhoeal Disease in the Next 15 Years

Although great strides have been made in reducing diarrhoea mortality, especially as a result of the increased use of oral rehydration therapy (ORT), diarrhoea remains the second leading cause of death in children under 5 years of age, after pneumonia.  It is responsible for an estimated 1.7 billion cases of diarrhoea, or on average 2.9 episodes/child/year, and an estimated 1.87 million deaths among children under 5 years of age.

The highest burden of disease is in children in the age range of 6–11 months: 4.5 episodes/child/year. It has been estimated that 50% of diarrhoea deaths can be attributed to persistent diarrhoea,7 and while ORT can prevent many deaths from acute diarrhoeal diseases,8 access to appropriate treatment is often limited in resource-poor settings.

The relationship between diarrhoeal disease and malnutrition is complex, though it is well accepted that malnourished children suffer more frequent episodes of diarrhoeal disease, while a child’s nutritional status is affected following a diarrhoeal episode.

A multiple country study found that 25% of stunting in children aged 24 months could be attributable to five or more diarrhoeal episodes experienced in the first 2 years of life. Malnutrition and stunting can lead to poorer school performance, early school drop-out and, as a result, lower economic well-being in later life. Over 440 million school days are missed annually due to WSH-related illnesses.

Extended exposure to faecal pathogens may, in part, cause environmental enteropathy, a postulated condition characterised by malabsorption, villus atrophy, crypt hyperplasia, T-cell infiltration and general inflammation of the jejunum. This chronic infection of the small intestine could explain why sanitation may have a stronger association with gains in growth than with reductions in diarrhoea incidence.