IDENTIFICATION OF THE MICROSPORIDIAN PARASITE, ENTEROCYTOZOON-BIENEUSI IN FECAL SAMPLES AND INTESTINAL BIOPSIES FROM AN AIDS PATIENT

The microsporidian parasite, Enterocytozoon bieneusi, is currently rec ognized as a potentially important cause of chronic diarrhoea in patie nts infected with the human immunodeficiency virus (HIV). Faecal conce ntrates from a 38-year-old, HIV-seropositive patient examined by light and electron microscopy revealed the presence of numerous microsporid ian spores. The structural characteristics of the spores were consiste nt with those previously described for Enterocytozoon bieneusi. Each s pore contained a single nucleus, a posterior vacuole and a polar filam ent with 6-7 overlapping coils which appeared in cross-section as a se ries of 3 doublets. Mature spores were surrounded by an inner unit mem brane, an electron-lucent endospore and a thin, electron-dense exospor e. The identity of the parasite was confirmed by the detection of uniq ue endogenous developmental stages in duodenal biopsies. Both prolifer ative and sporogonial plasmodia (meronts and sporonts) were observed a nd all stages were monokaryotic (single nucleus) and apansporoblastic (sporophorous vesicle absent). Proliferative and sporogonial plasmodia divided by plasmotomy and spore organelles (polar filament, attachmen t disc and polaroplast) were well developed prior to fission of the sp orogonial plasmodium.