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an order of protozoans of the class Cnidosporidia. There are more than 20 genera, comprising more than 300 species. They are intracellular parasites of animals, predominantly arthropods and fish. Microsporidian amoeboids reproduce asexually (by simple division and schizogony) in the cell cytoplasm of the animal host. After the sexual process (autogamy), formation of spores (sporogony) begins. The spores are usually oval (2–10 microns in length) and have a spirally wound polar thread that serves to embed the parasite in the tissue of a new host.

Microsporidians cause diseases, microsporidioses, in various animals. For example, microsporidians of the genus Nosema are the causative agents of nosematoses, and Nosema cuniculi is possibly the cause of the human disease multiple sclerosis. Many species of Microsporidia are parasites of fish and commercial arthropods. More than 100 species are beneficial as parasites of harmful arthropods, since they cause their mass destruction; the possibility of using these species for the biological control of pests is being investigated.


Zhiznzhivotnykh, vol. 1. Moscow, 1968.
Weiser, J. Die Mikrosporidien als Parasiten der Insekten. Hamburg-Berlin, 1961. I. V. Issi
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Fatal myositis due to the microsporidian Brachiola algerae, a mosquito pathogen.
Similarly, siphon muscle microsporidian parasites were generally of low prevalence or absent at all sites.
Laboratory host specificity testing of the fire ant microsporidian pathogen Vairimorpha invictae (Microporidia: Burenellidae).
Another method uses heat shock to cure insects of disease, an effective tool for eliminating some microsporidian species but not others.
Retrospective analysis by ISH revealed microsporidian organisms in the serosa of the intestines and surrounding reactive tissue in 7 of 16 animals with peritonitis of unknown cause.
Electron micrographs of skin and peritoneal fluid revealed microsporidian spores with features that were compatible with the genus Tubulinosema.
A microsporidian fire ant pathogen from South America, Kneallhazia (=Thelohania) solenopsae (Knell, Allen & Hazard), was first detected in the U.
8%) of the mussels had microsporidian infections, Steinhausii mytilovum (Mussel Egg Disease).
We report a case of microsporidian myositis caused by Tubulinosema sp.
2007), 2 species of microsporidian pathogens, and at least 3 kinds of viruses, are being investigated as potential fire ant biocontrol agents (Oi & Valles 2009).