Coccidia

Classification

Subclass of Apicomplexa.

General Information

Apart from only a few species, the coccidia are intracellular parasites which have a life cycle consisting of three phases: schizogony (asexual multiplication), gamogony (sexual phase, which proceeds in general as oogamy with macrogametes and microgametes), and sporogony (the zygote initiates another asexual reproduction leading to the production of numerous infectious sporozoites). In fecally-transmitted species (Eimeria, Fig. 1), the sporozoites are always included in resistant stages (oocysts and/or sporocysts), whereas in bite-transmitted groups (e.g., Plasmodium) oocysts are smooth and always located inside the vector.

Among the life cycles of the coccidia different types can be distinguished:

• Monoxenous development: The whole development is restricted to the tissues of a host individual. The species may be strictly host-specific (using only a single host species, e.g., Isospora spp., Eimeria spp.) or not (e.g., ...