Etiology and Epidemiology of Diarrhea

Infection causes (bacterial, viral, and parasitic) account for most cases of diarrhea. A potential pathogen can be identified in up to 70 % of acute diarrheas presenting at treatment facilities and in about 50 % of cases from the community. In general, the same pathogens are responsible for diarrhea worldwide, with only variations in the frequency of occurrence of each pathogen in different localities. The following are the commonest etiologic agents of diarrhea for all ages in decreasing order of prevalence obtained from pooled data worldwide: rotavirus, ETEC, shigella, campylobacter, Vibrio cholerae, and non-typhoidal salmonella. Similar organisms have been isolated from epidemiologic studies done in the Philippines. Other important viral agents of diarrhea are Norwalk and adenovirus; among parasites, cryptosporidium, Entamoeba histolytica, and Giardia intestinalis. A number of pathogens have also been associated with the presence of bloody stools and cases of persistent diarrhea. The usual pathogenic mechanisms for infectious diarrhea are toxin production and tissue invasion. Noninfectious causes of diarrhea include drugs, surgical conditions, systemic infections and food intolerance. [Phil