Persistent Diarrhoea and Intestinal Morphology - Alan Phillips
The Dietary Management of Persistent Diarrhoea & Malnutrition: Are we there yet? - Peter Sullivan
Micronutrients and Persistent Diarrhoea - Zulfiqar Bhutta

Peter B. Sullivan. University of Oxford, UK.

The WHO estimates that more than one third of the world's children are malnourished. 80% of the affected children live in Asia - mainly southern Asia. Significant advances in the prevention of malnutrition have been made, however, in recent years and these result from improvements in health and education and from successful nutritional intervention programmes. Diarrhoeal diseases are also major causes of morbidity with an estimated 12,600 deaths each day in children in Asia, Africa, and Latin America and the global mortality estimate is 3.3 million deaths per year; range, 1.5-5.1 million. With improved management of acute episodes of infectious diarrhoea, increased attention is now being given to persistent diarrhoea and its nutritional consequences and associated mortality. Risk factors for the development of persistent diarrhoea include young age, malnutrition, impaired immune function, recent introduction of milk feedings, prior antimicrobial therapy and infection with pathogenic strains of Escherichia coli. Descriptive epidemiology indicates that 3-20% of episodes of acute diarrhoea in children in developing countries become persistent and cause about one-third to one-half of all deaths from diarrhoea. The pathogenesis of persistent diarrhoea and malnutrition (PDM) remains uncertain but whatever the relative importance of nutritional, infective or allergic factors, it is likely that the underlying basis of this syndrome is prolonged injury to the small intestinal mucosa.

Once PDM has developed then nutritional management is the mainstay of treatment. Management entails an appreciation of: (i) the severity of malnutrition and its impact on cellular function and therefore on all the body's organ systems; (ii) the importance of the effects of microbial infection and (iii) the central role of prolonged damage to the organ of digestion and assimilation of the food - the small intestine. The management protocol which for malnutrition can be usefully divided into three phases:(i) Resuscitation; (ii) Stabilisation and (iii) Rehabilitation.

Ideally, successful rehabilitation leads not only to short term improvements in symptoms and weight gain but also to normal growth in the long term. Nutritional rehabilitation (NR) can be shown to produce a demonstrable improvement in small intestinal crypt cell proliferative activity in children with PDM. Follow-up studies on the progress of intestinal morphological changes after recovery from PDM, however, have demonstrated that gross changes in the small intestinal mucosal architecture could persist for up to one year late. A number of reports have indicated that diets formulated from traditional foods can be effective in the management of PDM. None of these diets, however, has been completely successful. Furthermore, in none of these studies was the effect of the diet on the restitution of intestinal integrity and function demonstrated. It is generally agreed that a more optimal dietary formulation yielding a higher success rate should be sought. Continued work is required to develop effective programmes that combine nutritional rehabilitation with maternal education so that long-term recovery of malnourished children will be ensured.

Zulfiqar Ahmed Bhutta. The Husein Lalji Dewraj Professor of Paediatrics, The Aga Khan University and Medical Center, Karachi, Pakistan

Despite evidence of reduced diarrhoea mortality, the incidence of diarrhoeal disorders in much of the developing world has hardly changed. In much of the developing world repeated episodes of diarrhoea are a frequent cause and consequence of malnutrition. In recent years, the demonstration of increased micronutrient losses with diarrhoea and dysentery are well recognised.

Hypovitaminosis A can affect general immune status, mucosal recovery patters and recovery from diarrhoea. Zinc deficiency may also alter intestinal repair mechanisms and increase intestinal permeability, thus delaying recovery from diarrhoea.

The risk of zinc deficiency in diarrhoea can be compounded manifolds by the pre-existing state of malnutrition and dietary factors such as phytates and poor intake of meats and dairy products. Thus a malnourished child with diarrhoea and poor dietary intake is already set up for multiple micronutrient deficiencies.

In recent years large scale studies and data evaluating the importance of micronutrients in diarrhoea have become available. The lack of convincing evidence of a therapeutic benefit of vitamin A administration in acute and persistent diarrhoea contrasts with the marked benefit on mortality seen in supplementation studies of at-risk or malnourished children. In contrast to vitamin A, the evidence supporting the benefit of zinc administration in acute diarrhoea is very strong and has been confirmed in diverse geographic locations. Although the evidence of a therapeutic benefit of zinc supplementation in persistent diarrhoea is less robust, a recent meta-analysis has also confirmed the beneficial effect of zinc on both severity and duration of persistent diarrhoea.