Entamoeba hartmanni

Last reviewed 01/2018

• Entamoeba hartmanni is, like Entamoeba coli, a non-pathogenic protozoa - may be found during stool examination and need to be differentiated from potentially pathogenic protozoa such as E. histolytica
  • found worldwide
• life cycle:
  • similar to that of E. histolytica but it does not have an invasive stage and does not ingest red blood cells
  • organisms exists as a motile trophozoite and a cyst
    • the cyst can survive outside the body and can be transmitted to humans via ingestion of contaminated food or water.
    • may also be spread directly by person-to- person contact (faecal-oral route)
    • whilst the cysts are in the small intestine, the trophozoites emerge, pass down into the colon and then multiply. Cysts and trophozoites are excreted in the faeces. Cysts are then ingested via the faecal-oral route/contaminated food/water
• laboratory features:
  • diagnosis is made by finding the characteristic cysts in an iodine stained, formol-ether concentration method or by detecting the characteristic trophozoites in a wet preparation or a permanent stained preparation
  • E. hartmanni is morphologically similar to E. histolytica, but has smaller cysts ( 10 µm on wet preparation; 9 µm on permanently stained smear) and and smaller trophozoites ( 12 µm on wet preparation; 11 µm on permanently stained smear) in comparison with E. histolytica
• clinical features:
  • presence of these organisms may imply host consumption of fecally contaminated water or food. However, there is no evidence that any of these protozoa have pathogenic potential, even in immunocompromised hosts
• management: seek expert advice from microbiologist