Apicomplexa
The
Apicomplexa are a large group of parasitic protists, most of which possess a unique organelle, a type of plastid called an apicoplast, and an
apical complex structure involved in penetrating a host's cell. They are unicellular, spore-forming, and exclusively parasites of animals. Motile structures such as flagella or pseudopods are present only in certain gamete stages. This is a diverse group including organisms such as the coccidia, gregarines, piroplasms, haemogregarines, and plasmodia. Diseases caused by apicomplexan organisms include, but are not limited to: ▪ Babesiosis ▪ Malaria ▪ Forms of coccidiosis including: ▪ Cryptosporidiosis ▪ Cyclosporiasis ▪ Isosporiasis ▪ Toxoplasmosis The name of the taxon
Apicomplexa is derived from two Latin words —
apex and
complexus — and refers to a set of organelles in the sporozoite. The older taxon
Sporozoa was created by SChrevel in 1971 and grouped the
Apicomplexa together with the Ascetosporea, Microsporidia and Myxosporida. This grouping is no longer regarded as biologically valid and its use is discouraged.