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plural chlamydozoa
: any of certain microorganisms related to the typical rickettsias
especially : an organism of the family Chlamydiaceae


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taxonomic synonym of chlamydia

Word History



after chlamydozoon

borrowed from New Latin, from chlamydo- chlamydo- + -zoon -zoon

Note: Name introduced by the German physician and radiologist Ludwig Halberstädter and the Czech parasitologist Stanislaus von Prowazek in "Über Zelleinschlüsse parasitärer Natur beim Trachom," Arbeiten aus dem Kaiserlichen Gesundheitsamte, vol. 26, Heft 1 (1907), pp. 44-47:"Wir hätten also einen Parasiten vor uns, der ein überwiegend intrazelluläres Dasein führt, und auf dessen Gegenwart die Zelle mit einer Hyperplasie von Plastin und Nucleolarsubstanzen antwortet, die bei einer ganze Reihe von Zellerkrankungen entweder ins Protoplasma übertreten, oder an Masse gewinnen und sich nur vergrössern … Bei der Lyssa (Negri, Volpino und Bertarelli), Vaccine (Guarnieri), Scharlach (Mallory), wahrscheinlich auch bei der Hühnerpest (Schiffmann und Paltauf) treten die den Nukleolen verwandten Substanzen dagegen im Protoplasma auf und umhüllen mantelartig die daselbst befindlichen korpuskulären Erreger (Initialkörperchen bei Vaccine und Scharlach) … Alle die erwähnten Erreger haben nichts mit den Bakterien gemeinsam … Es liegt aber auch kein Grund vor, sie den Protozoen einzureihen. Wir schlagen daher vor, sie unter dem Namen Chlamydozoa (chlamýs [Greek letters] Hülle, Mantel; zôon [Greek letters] Tier) zwischen beide Kreise zu stellen." ("Thus we would be dealing with a parasite leading an overwhelmingly intracellular mode of existence, and in its presence the cell reacts with a hyperplasia of plastin and nucleolar substances, which in a whole range of cellular diseases either cross over into the cytoplasm or only increase in mass … With rabies (Negri, Volpino and Bertarelli), cowpox (Guarnieri), scarlet fever (Mallory), and probably also with avian influenza (Schiffmann and Paltauf), on the other hand, substances akin to the nucleolus appear in the cytoplasm and envelop like a coat the corpuscular pathogens found there (initial bodies in the case of cowpox and scarlet fever) … None of the pathogens mentioned have anything in common with bacteria … But there is also no reason to class them with protozoa. Hence we suggest placing them between these two groups under the name Chlamydozoa (chlamýs covering, coat; zôon animal).") The pathogen causing trachoma, investigation of which was the subject of Halberstädter and von Prowazek's paper, is now regarded as a bacterium, Chlamydia trachomatis, with an idiosyncratic developmental cycle. On the basis of its occurrence in cellular inclusion bodies, Halberstädter and von Prowazek classed it with several other pathogens known from inclusion bodies under the name Chlamydozoa, though these have turned out to be viruses (the agents of rabies, cowpox, and scarlet fever). Some researchers took the pathogens and the inclusion bodies as virtually identical entities, hence treating chlamydozoon as a synonym of "inclusion body" (cf. Hugh W. Acton and W.F. Harvey, "The nature and specificity of Negri bodies," Parasitology, A Supplement to the Journal of Hygiene, vol. 4, no. 3 [October, 1911], pp. 255-72, with the editor's comments on the paper). Von Prowazek used Chlamadozoon as a true genus name for only one pathogen, the agent causing silkworm jaundice, which he named Chlamydozoon bombycis ("Chlamydozoa II. Gelbsucht der Seidenraupen," Archiv für Protistenkunde, 10. Band [1907], p. 363); this agent is now known to be a nuclear polyhedrosis virus. Chlamydozoon was revived as a taxon in the 1930's for the agent causing trachoma (Chlamydozoon trachomatis), but this name has since been disallowed—see note and references at chlamydia.

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Cite this Entry

“Chlamydozoon.” Dictionary, Merriam-Webster, Accessed 22 Mar. 2023.

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