Amoebas

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 29.10.2020

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Synonym(s)

Furniture for fame

History
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Löch, 1875; Osler, 1890; Councilman and Lafleur, 1891; Walker and Sellards, 1913; Brumpt, 1925; Diamond and Clark, 1993

Definition
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Single-celled parasites ( protozoa) of the genus Entamoeba. They do not have a solid form. Their locomotion and food intake is via cell plasma protuberances (pseudopodia), reproduction is by cell division.

Pathogen
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  • Apathogenic amoebae: apathogenic Entamoeba histolytica (new name Entamoeba dispar), Entamoeba moshkovskii, Entamoeba coli, Entamoeba hartmanni, Endolimax nana, Jodamoeba bütschlii, Dientamoeba fragilis (taxonomically belonging to the trichomonads), rare: Entamoeba chattoni (monkeys), Entamoeba polecki (pig).
  • Pathogenic amoebae: Entamoeba histolytica.
  • Route of infection: Faecal-oral uptake of cysts with contaminated food; release of smaller, vegetative forms, so-called minuta forms (trophozoites) from cysts in the intestine. Trophozoites multiply by division and form cysts, which are excreted with the stool in a mature, quadrenuclear state. When trophozoites penetrate the intestinal wall and phagocytise erythrocytes, they become so-called magnaforms.

Occurrence/Epidemiology
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Predominantly in warm countries with low hygienic standards, autochthonous infections in temperate zones are very rare (e.g. sluice-workers), occurrence in male homosexuals (oral-anal contacts, rectal lavage).

Diagnosis
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Therapy
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Note(s)
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The initial description of the pathogens has been made under many partial aspects:
  • Fedor Löch (1875): First description of dysentery and amoebae as a triggering agent.
  • William Osler (1890): first case description of diarrhoea with accompanying liver abscess.
  • Councilman and Lafleur (1891): confirmation of the connection between amoebae as a cause of diarrhoea and liver abscesses.
  • Walker and Sellards (1913): Proof of the pathogenicity of Entamoeba histolytica by enteral administration of cysts to volunteers.
  • Brumpt (1925): Presumption of the existence of invasive and non-invasive forms of amoebae.
  • Diamond and Clark (1993): biochemical, immunological and genetic differentiation of pathogenic and non-pathogenic amoebae.
  • WHO (1997): official confirmation of the classification.

Incoming links (3)

Amoebas; Magnaforms; Minuta forms;

Outgoing links (3)

Amebiasis; Amoebas; Protozoa;

Disclaimer

Please ask your physician for a reliable diagnosis. This website is only meant as a reference.

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Last updated on: 29.10.2020