Eimeria | |
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Eimeria maxima oocysts | |
Scientific classification | |
Domain: | Eukaryota |
(unranked): | Sar |
(unranked): | Alveolata |
Phylum: | Apicomplexa |
Class: | Conoidasida |
Order: | Eucoccidiorida |
Family: | Eimeriidae |
Genus: |
Eimeria Schneider, 1875 |
Type species | |
Eimeria falciformis (Eimer, 1870) Schneider, 1875 |
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Species | |
See text |
See text
Eimeria is a genus of apicomplexan parasites that includes various species capable of causing the disease coccidiosis in cattle and poultry, among other animals. The most prevalent species of Eimeria that cause coccidiosis in cattle would be E. bovis, E. zuernii, and E. auburnensis. In a young, susceptible calf it is estimated that as few as 50,000 infective oocysts can cause severe disease. The oocysts of what was later called Eimeria steidai were first seen by the pioneering Dutch microscopist Antoni van Leeuwenhoek (1632–1723) in the bile of a rabbit in 1674. The genus is named for the German zoologist Theodor Eimer (1843–1898).
The coccidia genera can be identified from oocysts:
Eimeria - four sporocysts, each containing two sporozoites
Wenyonella - four sporocysts, each containing four sporozoites
Tyzzeria - eight sporozoites, not contained in sporocysts
Isospora - two sporocysts, each containing four sporozoites
The Eimeria lie within the family Eimeriidae. This genus has ~75% of the species within this family, and it is the most specious of the genera of the Apicomplexia with 1,700 described species.
Attempts to subdivide this large taxonomic unit into separate genera have been made.
The Eimeria of fish have been divided into four genera based on available morphologic and life cycle data.
Eimeria: these species are tetrasporocystic with dizoic, nonbivalved sporocysts with or without Stieda bodies. This new genus retains the majority of the species.
Goussia (Labbe 1896): These species are tetrasporocystic, dizoic, lack Stieda bodies, and have sporocyst walls consisting of two valves joined by a longitudinal suture. This genus contains about 20 species.
Crystallospora (Labbe 1896): The species in this genus is tetrasporocystic and dizoic, and have dodecahedral sporocysts composed of two hexagonal, pyrimidal valves joined at their bases by a suture. This genus contains a single species, Crystallospora cristalloides (Thelohan 1893).