Malnutrition as an enteric infectious disease with long-term effects on child development

Abstract

Malnutrition is a major contributor to mortality and is increasingly recognized as a cause of potentially lifelong functional disability. Yet, a rate-limiting step in achieving normal nutrition may be impaired absorptive function due to multiple repeated enteric infections. This is especially problematic in children whose diets are marginal. In malnourished individuals, the infections are even more devastating. This review documents the evidence that intestinal infections lead to malnutrition and that malnutrition worsens intestinal infections. The clinical data presented here derive largely from long-term cohort studies that are supported by controlled animal studies. Also reviewed are the mechanisms by which enteric infections lead to undernutrition and by which malnutrition worsens enteric infections, with implications for potential novel interventions. Further intervention studies are needed to document the relevance of these mechanisms and, most importantly, to interrupt the vicious diarrhea-malnutrition cycle so children may develop their full potential.

Figure 1. Effects of repeated diarrheal episodes on childhood growth curves

A Illustrative case of a child in Guatemala, from Mata (1978). B Three illustrative cases from a group of 6–21-month-old girls in Pacatuba, Ceara, Brazil, from Leslie and de Souza (1996). Values on the vertical axes are weight in kg; values on the horizontal axes are age in months. D = duration of diarrheal illness

Figure 1. Effects of repeated diarrheal episodes on childhood growth curves

A Illustrative case of a child in Guatemala, from Mata (1978). B Three illustrative cases from a group of 6–21-month-old girls in Pacatuba, Ceara, Brazil, from Leslie and de Souza (1996). Values on the vertical axes are weight in kg; values on the horizontal axes are age in months. D = duration of diarrheal illness

Figure 2. Effect of diarrhea on catch-up growth

Figure from Schorling and Guerrant (1990)

Figure 3. Synergistic effects of malnutrition and Cryptosporidium infection on ileal architecture (hemotoxylin and eosin; 10×; at 14 days old; 8 days after infection).

Figure from Coutinho et al. (2008)

Figure 4. Gut-trophic nutritional approaches to breaking the vicious cycle between malnutrition and diarrhea by repairing the intestinal mucosa

Outcome measures that can help assess these impacts as well as potential interventions include growth and anthropometry (especially HAZ scores), IQ and learning abilities, repeated diarrheal illnesses, intestinal absorptive and barrier function (i.e., using lactulose-mannitol ‘permeability’, intestinal inflammation (using quantitative fecal lactoferrin testing), and innate and acquired immune function.