Abstract
This review examines and compares host defence mechanisms during intestinal infection with three types of organisms: a virus, a bacterium and a nematode parasite (ie, transmissible gastroenteritis virus [TGEV], Helicobacter jejuni and Trichinella spiralis). Diarrhea is commonly associated with all of these infections. It appears that T spiralis initiates the most elaborate defence system of the three organisms, involving full range humoral and cellular immunity, as well as mucus hypersecretion, epithelial alterations, altered gut motility and parasite impairment (morphological and physiological). In contrast, intestinal defence against H jejuni and TGEV involves fewer components. The latter seems to initiate the most rudimentary host response. Despite such differences, these mechanisms exhibit many similarities, thus further illustrating the relatively limited repertoire of defence systems that the intestine can mount. The mediators translating the insult of any intestinal pathogen into a common response deserve further investigation.