Observations on the intracytoplasmic microsporidian Steinhausia mytilovum, a parasite of mussel (Mytella guyanensis) occytes from the Amazon river estuary

Microsporidians (Microsporidia) can parasitize commercially important marine mollusks, including bivalves. In this report, we provide a brief description of the ultrastructure of the microsporidian Steinhausia mytilovum that occurs in the oocyte cytoplasm of the mussel Mytella guyanensis (Mollusca, Bivalvia, Mytillidae) from the Amazon river estuary. Mussel ovaries were fixed, stained and examined using differential interference contrast optics (DIC). The parasite developed in an intracytoplasmic vacuole containing a variable number of spores (up to 14). Mature spores were 2.3 ± 0.3 ìm long and 1.7 ± 0.3 ìm wide (n = 25 each). Transmission electron microscopy revealed two types of intracytoplasmic vacuoles, one containing spores with a light (less dense) cytoplasm that corresponded to the maturation phases, and the other containing mature, dense, granular spores that showed specific microsporidian structures. The anchoring disc and the anterior zone of the polar filament were surrounded by the polaroplast. The polar filament was isofilar and consisted of a double (rarely triple) coil with 9-10 turns. The ultrastructural morphology of these spores suggested that they belonged to S. mytilovum.

Estudio morfologico de Enterocytozoon bieneusi en pacientes con SIDA y diarrhea cronica / Morphological study of Enterocytozoon bineousi in patients with AIDS and chronic diarrhea

Microsporidia are protozoan parasites responsible for significant gastrointestinal disease in patients infected with the human inmunodeficiency virus. We reporte the clinical features of three patients with chronic diarrhea and intestinal microsporidiosis caused by Enterocytozoon bieneusi. The average value for CD4 in these patients was ó 50 cells/mm3. The spores were detected in smears from stool samples and duodenal aspirates stained with trichrome blue in all patiens. Light microscopy of semithin plastic sections revealed parasites and spores in the enterocytes and were associated with villous atrophy (2 out of 3). Thin section-electron microscopy showed a variety of developmental stages of the microsporidio. Patients treated with Albendazole had an unsatisfactory clinical response to therapy. Enterocytozzon bieneusi infection may be an important cause of diarrhea in patiens with AIDS in our country.