Diarrhoeal disease: current concepts and future challenges. Malnutrition and infection

In individual children in developed countries it is possible to follow a sequence of infection of the gastrointestinal tract leading to chronic diarrhoea which, if it long persists, may in turn lead to undernutrition. Both in individuals and epidemiologically in developing countries it is, by contrast, often difficult to be certain whether infection precedes under-nutrition or vice versa. Chronic diarrhoea is heterogeneous and aetiology varies from community to community. Unlike acute diarrhoea, for which there is highly effective unitary therapy (oral rehydration therapy), diverse therapies are required for chronic diarrhoea based on specific diagnoses and so render community strategies difficult. The importance of adequate calorie intake is emphasized but when there is intolerance to food ingested this is counter-productive. The relative importance of post-infective food intolerance remains controversial and in many communities is unknown. Increasing emphasis is now given to the role of infection in pathogenesis of diarrhoea and malnutrition, e.g. the acquired immune deficiency syndrome and Helicobacter pylori. Hospital-based case studies including small intestinal biopsy in individual communities, by virtue of an 'iceberg effect', may prove useful for insights into aetiology and pave the way for interventions, e.g. antibiotics or dietary therapy.