MUCOSAL ABNORMALITIES IN MICROSPORIDIOSIS

Objective: To determine the prevalence of microsporidiosis in HIV-infe cted patients with and without diarrhoea and to characterize alteratio ns in mucosal architecture and brush border enzyme activities in patie nts with microsporidiosis. Patients: A total of 259 HIV-infected patie nts undergoing oesophagogastroduodenoscopy because of diarrhoea (n = 1 23) or other symptoms (n = 136) were studied. Methods: Patients were e valuated for the presence of microsporidia by electron microscopy of d uodenal biopsies. Brush border enzyme activities were measured by hist ochemistry and mucosal architecture was determined by three-dimensiona l morphometry in biopsies from patients with microsporidiosis and comp ared with biopsies from a subgroup of HIV-infected patients with or wi thout other enteropathogens. Results: Enterocytozoon bieneusi was dete cted in 17 patients and Encephalitozoon intestinalis was detected in t wo patients. Microsporidiosis was significantly more frequent in patie nts with chronic diarrhoea (19.1%; P < 0.0001) or in patients with acu te diarrhoea (7.2%; P = 0.04) than in patients without diarrhoea (1.5% ). Microsporidiosis was associated with lactase deficiency (P = 0.03) and a reduced activity of alkaline phosphatase (P = 0.028) and alpha-g lucosidase (P = 0.025) at the basal part of the villus compared with b rush border enzymes in patients without enteropathogens. Patients with microsporidia had reduced villus height (P = 0.043) and a villus surf ace reduced by 40% (P = 0.004) compared with patients with enteropatho gens other than microsporidia. Conclusions: Our study confirms the ass ociation between microsporidia and diarrhoea. The pathophysiologic mec hanism by which microsporidia cause diarrhoea appears in part to be ma labsorption, caused by a reduction of absorptive mucosal surface and i mpairment of enterocyte function.