Microsporidia are highly-specialized obligate-intracellular parasitic fungi that are traditionally identified in the clinical parasitology laboratory. There are multiple genera that are infectious to humans, with the most common being Enterocytozoon bieneusi and Encephalitizoon species. They are seen in human specimens as minute (0.7 to 1.4 micrometer) spores that stain bright red with chromotrope-based stains such as Ryan's trichome blue. Often, a central stripe (arrows) may be seen running perpendicular to the long axis of the spore.