Diarrhea in Helminthic Infections

Enteric helminths are among the most prevalent parasites of humankind, yet only scanty information exists about their effects on the gastrointestinal tract of their hosts. Specifically, there is little agreement on which worms definitely cause diarrhea. The available evidence sug-gests that five helminthic parasites are associated with human diarrheal disease: Trichinella spiralis (early phases of infection), Trichuris trichiura, Strongyloides stercoralis, Capillaria philip-pinensis, and Schistosoma (particularly Schistosoma mansoni). All these parasites have an inva-sive phase during which adult worms, their eggs, or their larvae establish intimate contact with the host's intestinal mucosa and elicit strong local inflammatory responses resulting in various structural and functional alterations of the gut. In contrast, strictly intraluminal worms do not seem to interfere with their hosts ' intestinal structure and function to a degree sufficient to cause diarrhea. Intestinal helminthiases are among the most prevalent chronic infections of humankind. Although large-scale epide-miological studies have been few and frequently incomplete, it has been estimated that approximately half of the world'