[Physiopathology of Rotavirus diarrhea]

The rotavirus is the major cause of infantile gastroenteritis. The virus infects the mature enterocytes of the villus tip of the small intestine and induces a watery diarrhea. Diarrhea can occur in the absence of histological changes in the intestine, and, conversely, the histological changes can be asymptomatic. Rotavirus decreases the activities of digestive enzymes at the apical brush border membrane and inhibits Na+ -solute cotransport systems. Accumulation of carbohydrates in the intestinal lumen as well as malabsorption of nutrients and a concomitant inhibition of water absorption can lead to a malabsorptive component of diarrhea. Since the discovery of the NSP4 enterotoxin, several hypotheses have been proposed in favour of an additional secretion component in the pathogenesis of diarrhea. Rotavirus induces a moderate net chloride secretion at the onset of the diarrhea. The mechanisms appear to different from those used by bacterial enterotoxin that cause pure secretory diarrhea. Rotavirus stimulated C1- reabsorption in villi, and failed to stimulate C1- secretion in crypt. Intestinal villi could secrete chloride as a result of rotavirus infection. The chloride secretory response is regulated by a dependant calcium signalling pathway induced by NSP4. The overall response is weak, suggesting that NSP4 may exert both secretory and subsequent antisecretory actions, hence limiting C1- secretion.