MICROSPORIDIA OF THE GENUS TRACHIPLEISTOPHORA-CAUSATIVE AGENTS OF HUMAN MICROSPORIDIOSIS - DESCRIPTION OF TRACHIPLEISTOPHORA-ANTHROPOPHTHERA N. SP. (PROTOZOA, MICROSPORIDIA)

Trachipleistophora anthropophthera n. sp., was found at autopsy in the brain of one and in the brain, kidneys, pancreas, thyroid, parathyroi d, heart, liver, spleen, lymph nodes, and bone marrow of a second pati ent with AIDS. The parasite is similar to the recently described T. ho minis Hollister, Canning, Weidner, Field, Kench and Mariott, 1996, in having isolated nuclei, meronts with a thick layer of electron dense m aterial on the outer face of their plasmalemma and sporogony during wh ich spores are formed inside a thick-walled sporophorous vesicle. In c ontrast to T. hominis, this species is dimorphic as it forms two kinds of sporophorous vesicles and spores: Type I-round to oval polysporous sporophorous vesicle, 7-10 mu m in size, usually with eight spores (3 .7 X 2.0 mu m), thick endospores, subterminal anchoring disc and aniso filar polar filaments forming seven thicker and two thinner terminal c oils. This type of sporophorous vesicle is associated with 25-30 nm fi laments extending into the host cell cytoplasm. Type II-smaller, bispo rous sporophorous vesicle (4-5 X 2.2-2.5 mu m) with two, nearly round, thin-walled spores, 2.2-2.5 X 1.8-2.0 mu m in size, having 4-5 isofil ar coils. No outside filamentous elements are associated with the bisp orous sporophorous vesicle. Both types of sporophorous vesicles were c ommon in the infected brain tissue and could be found within the same cell. The newly described species, together with T. hominis and previo usly reported Pleistophora-like parasites from human muscle, likely re present a group of closely related human microsporidia.