Amoebic colitis A06.0

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 29.10.2020

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Synonym(s)

Amoeba dysentery; invasive intestinal amebiasis

Definition
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Intestinal infection with the protozoon Entamoeba histolytica.

Classification
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Entamoeba histolytica.

Occurrence/Epidemiology
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  • Worldwide prevalence: about 50 million people worldwide contract invasive amoebiasis annually, up to 100,000 deaths annually (WHO, 1997).
  • Occurrence: mainly in warm countries with low hygienic standards, autochthonous infections in temperate zones very rare (e.g. sewage workers), occurrence in male homosexuals (oral-anal contact, rectal lavage).

Etiopathogenesis
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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 bifurcation 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.

Clinical features
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  • Colon: after invasion of trophozoites into the mucosa, undermined ulcerations, so-called bottleneck or canteen ulcers, develop that reach down to the submucosa.
  • Abdominal pain, fever, "raspberry-jelly", slimy-bloody diarrhoea, milder forms: mushy-watery diarrhoea (more frequent), ulcers reaching the submucosa (so-called bottleneck or canteen ulcers), gradual development over several weeks to years. Chronic courses are possible.
  • Perforation
  • Toxic Megacolon
  • Amoeboma.

Diagnosis
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  • In the chair:
    • Stool culture (to exclude simultaneous bacterial infections)
    • Stool microscopy (sensitivity of 70%): MIFC method in stool (preferably in native stool, fresh stool/mucus flake [in 3 stool samples]): Microscopic detection of cysts, minota forms and magnaforms in stool. Pathogenic and apathogenic forms of intestinal lumen cannot be differentiated, characteristics of cysts: E. histolytica larger than 10 µm, E. histolytica maximum 4 nuclei. Detection of magnaforms is proven by amoebic colitis.
    • Antigen detection (ELISA, sensitivity comparable with microscopy)
    • PCR (highest sensitivity)
  • In serum (indication of invasion):
    • Serum antibodies (ELISA)
    • Transaminases, cholestasis parameters
    • Inflammation parameters
    • Blood count
    • Electrolytes.
  • Imaging (abscess, perforation, toxic megacolon):
    • Abdominal sonography
    • Computer tomography
    • Colonoscopy.

Differential diagnosis
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  • Diseases that may be associated with similar clinic:
    • Diarrhoea induced by bacterial toxins
    • Shigellose
    • Salmonellosis
    • Campylobacter infection
    • Yersiniosis
    • Chronic inflammatory intestinal diseases
    • Malignant tumors.

Complication(s)
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  • Perforation with peritonitis
  • Toxic megacolon
  • Amoeboma.

Therapy
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  • Standard: Metronidazole 3 times/day 10 mg/kg bw (max. 3 times/day 800 mg) i.v. or orally over 10 days (dosage for adults and children).
  • In mild cases: Tinidazole 2 g/day orally for 5 days (children: 30 mg/kg bw/day, maximum 2 g/day). Tinidazole is no longer approved in Germany, but is available from pharmacies abroad ( off-label use).
  • Subsequently cyst treatment: Paromomycin 3 times/day 500 mg/day p.o. for 9-10 days (children: 10 mg/kg bw/day).
  • Alternatively: Diloxanidfuroat, Nimorazol, Chloroquin.
  • In pregnant women: treatment indicated (however, 5-nitroimidazole should not be given in the 1st trimester).

Prophylaxis
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  • Food hygiene (ice cubes, salads, ice cream, open juices)
  • Avoid oral-anal sexual contacts and rectal lavage.

Aftercare
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  • Control of the success of therapy: in severe cases: blood count, liver values, cholestasis and inflammation parameters during and after treatment, time intervals according to the severity of the disease.
  • Stool examination: 6 weeks after the end of treatment.

Note(s)
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Current therapy recommendations can be found in the AWMF guidelines.

Literature
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  1. Annesley J (1828) Researches into the causes, nature and treatment of the more prevalent diseases of warm climates generally. Longman, Rees, Orme, Brown and Green, London, Vol. 2 p. 247
  2. Budd G (1857) On diseases of the liver. Churchill, London, United Kingdom
  3. Burchard GD et al (2003) Therapy of tropical diseases after returning from travel. Internist 44: 633-642
  4. Kucik CJ et al (2004) Common intestinal parasites. On Fam Physician 69: 1161-1168
  5. Losch FA (1975) Massive development of amebas in the large intestine. Translation from the original in Russian. Am J Trop Med Hyg 24: 383-392

Incoming links (1)

Amebiasis;

Outgoing links (4)

Amebiasis; Amoebom; Off-label use; Protozoa;

Disclaimer

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

Authors

Last updated on: 29.10.2020