RT Book, Section A1 Dunn, James J. A2 Kline, Mark W. SR Print(0) ID 1182937294 T1 Microsporidiosis T2 Rudolph's Pediatrics, 23e YR 2018 FD 2018 PB McGraw-Hill Education PP New York, NY SN 9781259588594 LK accesspediatrics.mhmedical.com/content.aspx?aid=1182937294 RD 2024/03/29 AB Microsporidia is a nontaxonomic term referring to an extensive group of unicellular, spore-forming eukaryotic organisms now reclassified in the kingdom Fungi. Microsporidia lack mitochondria, are obligate intracellular parasites, and have no metabolically active stages outside the host cell. The phylum Microsporidia encompasses more than 160 genera and 1300 species that are pathogenic in nearly all animal phyla and even some protists. To date, at least 16 species of microsporidia have been implicated in human infections (Table 297-1). Mature microsporidial spores possess a characteristic coiled extrusion apparatus consisting of a polar tubule anchored to an anterior disk within the spore. The polar tubule is capable of penetrating the host cell membrane, after which the infective spore contents (sporoplasm) can be injected into the cytoplasm and the reproductive life cycle begins (Fig. 297-1).