Intestinal microsporidiosis in a Chilean patient with acquired immunodeficiency syndrome (AIDS).

Summary A 24-year-old male patient with AIDS diagnosed in 1989, and with several episodes of pneumocystosis, was admitted because of a chronic diarrheic syndrome and severe epigastric pain. Endoscopy showed a granular duodenal mucosa. Light microscopy showed a moderate villous atrophy with round-cell inflammatory infiltration of the chorion. Giemsa, Ziehl-Neelsen, and Gram stains showed microsporidial spores measuring between 1.5 and 2 μn in the supranuclear cytoplasm of some enterocytes. Electron microscopy showed sporoblasts and spores consistent with Enterocytozoon bieneusi , with an apparently non-tubular, rather electron-dense polar filament showing up to 7 coils and also a microtubular internal structure with annular disposition, a finding which has not been adequately emphasized in the pertinent literature, probably representing a contractile property of the polar filament, rather than a mere duct for the parasitic sporoplasm to be inoculated.