Trichuriasis: localized inflammatory responses in the colon.

Most patients with trichuriasis have light worm burdens. Data regarding the inflammatory response to Trichuris worms in the colon of lightly infected persons are scant. Nine patients whose Trichuris infection was found by colonoscopy had biopsies taken from a site adjacent to visible worms and from a second site some 20 cm distally. The biopsies were studied by routine and immunohistochemical methods. None of the biopsies showed mucosal ulceration, significant congestion, fibrosis, gland distortion or goblet cell mucin depletion. There was no difference between worm and worm-free sites in terms of edema, lymphoid follicles or epithelial slough. Worm sites had higher numbers of eosinophils, neutrophils and total inflammatory cells and lower numbers of plasma cells. However there was no difference in lymphocyte, mast cell, and B- and T-cell counts between the two sites. This suggests that the T. trichiura worm incites a local inflammatory response involving eosinophils and neutrophils, even when the colon has only a light burden of worms.