ABSTRACT
Several species belonging to the genus Anncaliia (Brachiola) that usually parasitize insects have been found recently to infect humans, causing keratoconjunctivitis, myositis, and dermatitis. These are included under the phylum Microsporidia, which are ancient, spore-forming, mitochondria-lacking, obligate, intracellular, eukaryotic organisms that were previously considered as protozoa. The infective stage is the spore, which is Gram-positive, environmentally resistant, and characterized by the presence of a unique apparatus, the polar tube, which coils around the sporoplasm, the infectious organelle. When the spore is ingested, the polar tube is extruded with great force, penetrating a susceptible host cell and injecting it with the sporoplasm. Because of these unique characteristics, microsporidia were classi–ed in a separate phylum, Microsporidia [1,2]. The ribosomes of microsporidia resemble prokaryotic ribosomes in terms of size but lack a 5.8S subunit [3]. Recent whole genome sequencing of Encephalitozoon cuniculi [4] and other microsporidians as well as the phylogenetic analysis of α tubulin and β tubulin genes [5] has placed these organisms along with fungi [6].
