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Related to Apicomplexa: Ciliophora, Ciliata, Protozoa, plasmodium


(spôr'əzō`ə), phylum of unicellular heterotrophic organisms of the kingdom ProtistaProtista
or Protoctista
, in the five-kingdom system of classification, a kingdom comprising a variety of unicellular and some simple multinuclear and multicellular eukaryotic organisms.
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. Unlike most other protozoansprotozoan
, informal term for the unicellular heterotrophs of the kingdom Protista. Protozoans comprise a large, diverse assortment of microscopic or near-microscopic organisms that live as single cells or in simple colonies and that show no differentiation into tissues.
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, sporozoans have no cilia or flagella. All species are parasitic and have elaborate life cycles, often requiring more than one host. The best-known sporozoan is Plasmodium falciparum, the causative organism of malariamalaria,
infectious parasitic disease that can be either acute or chronic and is frequently recurrent. Malaria is common in Africa, Central and South America, the Mediterranean countries, Asia, and many of the Pacific islands.
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A subphylum of Protozoa, typically with spores. The spores are simple and have no polar filaments. There is a single type of nucleus. There are no cilia or flagella except for flagellated microgametes in some groups. In most Sporozoa there is an alternation of sexual and asexual stages in the life cycle. In the sexual stage, fertilization is by syngamy, that is, the union of male and female gametes. All Sporozoa are parasitic. The subphylum is divided into three classes—Telosporea, Toxoplasmea, and Haplosporea. See Haplosporea, Protozoa

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a class of parasitic protozoans including about 2,000 species. The class was identified in 1879 by the German scientist R. Leuckart. Sporozoans are characterized by primary alternation of generations and asexual and sexual reproduction. The principal stages in the life cycle are schizogony (asexual reproduction by multiple segmentation), gamogony (gamete formation and fertilization), and sporogony (formation of spores and sporozoites from the zygote). Schizogony is absent in most gregarines. Sporozoans parasitize the cells, tissues, and cavities of animals and humans. Schizogony leads to an increase in the number of parasites in the body of the host, and sporogony ensures infection of other individuals of the host species. Zygotic reduction is observed in all sporozoans: the first division of the zygote nucleus during sporogony is meiotic, and all the subsequent stages are haploid.

Some sporozoans, for example, most coccidians, have a single host; their distribution is external and by means of oocysts, which are covered with protective sheaths. Other sporozoans, including Plasmodium (the causative agents of malaria), have two hosts: asexual reproduction occurs in one, and the sexual process and sporogony occur in the other. In these sporozoans transmission of the parasite from one host to the other is effected by a bite or by ingestion of the host by another animal. For example, malaria is transmitted to man by means of a mosquito bite, and Haemogregarina is transmitted when a lizard eats an infected tick. In such cases the stages with protective sheaths are absent, and tiny wormlike mononuclear cells—sporozoites—develop in sporocysts and infect the vertebrate host.

Sporozoans include gregarines and Coccidiomorpha; the latter comprise Coccidia and Haemosporidia. Among the haemosporidians are the causative agents of a number of serious human disease (malaria, toxoplasmosis) and diseases of domestic mammals and birds (coccidiosis).


Zhizn zhivotnykh, vol. 1. Moscow, 1968. Pages 116–29.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


(invertebrate zoology)
A subphylum of parasitic Protozoa, typically producing spores during the asexual stages of the life cycle.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The Eimeriidae (Apicomplexa) of raptors: review of literature and description of new species of genera Caryospora & Eimeria.
(Apicomplexa: Eimeriidae) from the eastern chipmunk (Tamias striatus) in Pennsylvania with a description of one new species.
The troublesome parasites--molecular and morphological evidence that Apicomplexa belong to the dinoflagellate-ciliate clade.
(Apicomplexa: Eimeriidae) em trinca-ferrosverdadeiros Saltador similis d'Orbigny, Lafresnaye (Passeriformes: Cardinalidae) mantidos em cativeiro no Municipio de Valenca, Estado do Rio de Janeiro, Brasil.
(Apicomplexa), parasite of the mussel Mytella guyanensis (Mytilidae) from the Amazon Estuary and description of its oocysts.
It was found that the initial contact of the apical region of infective forms of protozoa of the phylum Apicomplexa is fundamental to trigger host cell invasion (Nicholas et al., 1983).
Instead, the closest match in BLAST (www.ncbi.nlm.nih.gov/blast/Blast.cgi) analyses based on the entire sequence was Colpodella tetrahymenae (89% identity), a member of a genus that is closely related to Apicomplexa but that has never, to our knowledge, been found to infect animals or people (GenBank accession no.
Chapters are devoted to 15 types of organisms: gastrointestinal protozoa, kinetoplastids, apicomplexa, and free-living protozoa.
Presencia de Plasmodium brasilianum (Apicomplexa, Plasmodidae) en el mono congo (Alouatta palliata, Primates: Cebidae) de Costa Rica.