Diarrhoeal diseases

In developing countries, diarrhoeal diseases among children are caused by a wide variety of pathogens, including rotavirus, Escherichia coli, Shigella, Vibrio cholerae, Salmonella and Entamoeba histolytica. The epidemiology, clinical features, immunology and pathogenesis of diarrhoea may differ according to characteristics of the pathogen, such as production of toxins, tissue invasion, fluid and electrolyte loss and location of infection. Vitamin A supplementation or fortification has been shown to reduce the morbidity and mortality of diarrhoeal diseases among preschool children in developing countries. The reduction in diarrhoeal disease mortality appears to account for most of the reduction in overall mortality when vitamin A is given through fortification or supplementation on a community level. Clinical vitamin A deficiency is associated with diarrhoeal disease in children (Sommer et al., 1984; Brilliant et al., 1985; DeSole et al., 1987; Gujral et al., 1993; Schaumberg et al., 1996). Large community-based clinical trials of vitamin A supplementation in Tamil Nadu, Nepal and Ghana show that vitamin A has a major impact upon the overall mortality of diarrhoeal disease but not on pneumonia in preschool children (Beaton et al., 1993; Vitamin A and Pneumonia Working Group, 1995). The severity of diarrhoeal disease was reduced by vitamin A supplementation in a clinical trial in Brazil (Barreto et al., 1994). Urinary losses of vitamin A during Shigella infection may be substantial in some children (Mitra et al., 1998), and vitamin A supplementation (60 mg RE) has been shown to reduce morbidity in children with acute shigellosis (Hossain et al., 1998). Although improvement of vitamin A status has been shown to protect against diarrhoeal diseases, it is not clear whether this is a general effect against all diar-rhoeal pathogens or only against certain types of pathogens.

0 0

Post a comment