NutritionNutrition and Diarrheal Disease and Enteric Pathogens

Malnutrition, a public health problem for the low- and middle-income countries, mainly affects young children. It contributes significantly to their morbidity and mortality and makes them vulnerable to diarrheal diseases and enteric infections through various mechanisms. Protein calorie and micronutrient deficiencies increase the risk of exposure to diarrhea causing pathogens through placing affected persons in high-risk environments, e.g., hospitals. It also disrupts immune mechanisms at various levels leading to diminished ability to prevent pathogens from entering the body and mounting a sufficiently strong and appropriate response when required. For example, malnutrition reduces the capacity to maintain a robust gut mucosal barrier needed to prevent intrusion of microbes deeper into the body, and it diminishes the production of inflammatory response hormones, cells, and antibodies that are needed to eliminate the invading organisms. Therefore, enteric infections progress faster, have greater severity, and worse outcomes. Even when timely treatments are provided, they are less effective in malnourished compared with well-nourished individuals. Antimicrobial interventions are frequently required, which though lifesaving in most instances, are known to deteriorate the already stressed gut microbiome, worsening the gut’s resistance capabilities. Greater harm inflicted by the infections in the presence of malnutrition further aggravates existing malnutrition initiating a vicious cycle. It is important to note, however, that some deficiencies reduce the risk of disease. For example, the risk of amebic infection is lower in the presence of iron deficiency and that some components of immunity are retained despite lack of energy. Further research into specific areas is required to identify new intervention targets.