- Protozoan species, genus Entamoeba.
- E. histolytica is morphologically similar to E. dispar, E. moshkovskii, and E. bangladeshi.
- Histolytic - histo + lyein (Greek) to loosen, trophozoites contain cytolytic and proteolytic enzymes, including collagenase and proteinases, and lyze neutrophils and macrophages.
- Cysts are ingested; excystation occurs in the distal ileum and cecum. Motile trophozoites are released and migrate to the large intestine.
- Trophozoite surface protein and key virulence factor, Gal/GalNAc lectin, mediates adherence to host cells.
- Fecal anti-Gal/GalNAc lectin IgA protective against infection.
- Disease occurs in a minority (10%) of infections.
- Cysts found in contaminated water or food. Cysts remain viable outside host in water, soil, and sewage for weeks or months.
- Infecting dose is fewer than 10 cysts.
- Occurs primarily in developing countries, also seen in immigrants from and travelers to endemic areas and those with oral-anal or oral-fecal contact.
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Last updated: July 4, 2021
Spacek, Lisa A. "Entamoeba Histolytica." Johns Hopkins ABX Guide, The Johns Hopkins University, 2021. Pediatrics Central, peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540199/all/Entamoeba_histolytica.
Spacek LA. Entamoeba histolytica. Johns Hopkins ABX Guide. The Johns Hopkins University; 2021. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540199/all/Entamoeba_histolytica. Accessed November 28, 2023.
Spacek, L. A. (2021). Entamoeba histolytica. In Johns Hopkins ABX Guide. The Johns Hopkins University. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540199/all/Entamoeba_histolytica
Spacek LA. Entamoeba Histolytica [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2021. [cited 2023 November 28]. Available from: https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540199/all/Entamoeba_histolytica.
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