This document discusses Entamoeba histolytica, a pathogenic species of amoeba that causes amebiasis in humans. It exists in two forms, the trophozoite which is the actively feeding stage, and the cyst, which is the dormant resistant stage. Transmission occurs when contaminated food or water is consumed, containing the cyst form which can survive outside the body. The trophozoites colonize the large intestine where they can invade the mucosa and cause intestinal lesions or abscesses. Diagnosis involves examining stool samples microscopically for the presence of motile trophozoites or cysts. Treatment involves medications like metronidazole which act against the amoeba at both intestinal

1. EntamoebaEntamoeba

2. Entameoba hitolyticaEntameoba hitolytica
 Pathogenic speciesPathogenic species E. histolyticaE. histolytica
 Non Pathogenic SpeciesNon Pathogenic Species E. disparE. dispar

3. Entamoeba histolyticaEntamoeba histolytica
Discovered in 1875 by Losch in St Petersburg,Discovered in 1875 by Losch in St Petersburg,
RussiaRussia

4. Geographical DistributionGeographical Distribution
 World wide in prevalenceWorld wide in prevalence
 Found wherever sanitation is poorFound wherever sanitation is poor
 33rdrd
leading parasitic disease – supercede only beleading parasitic disease – supercede only be
Malaria and SchistosomiasisMalaria and Schistosomiasis
 Globally – 50 million infections/ years &Globally – 50 million infections/ years &
 100 000 deaths100 000 deaths

5. EntamoebaEntamoeba
Exists in two forms i.e.Exists in two forms i.e.
 TrophozoiteTrophozoite
 CystCyst

6. Entamoeba histolyticaEntamoeba histolytica
 Active, feeding stageActive, feeding stage
 Growing stageGrowing stage
 Amoeboid with bluntAmoeboid with blunt
pseudopodiapseudopodia
 Non-foamy cytoplasmNon-foamy cytoplasm
 Uninucleated; nucleusUninucleated; nucleus
with fine peripheralwith fine peripheral
chromatin granules,chromatin granules,
small central endosomesmall central endosomeTrophozoite: 20-30 µm

7. Entamoeba histolyticaEntamoeba histolytica
 Dormant/resistantDormant/resistant
stagestage
 SphericalSpherical
 1-4 nuclei, (4 in mature1-4 nuclei, (4 in mature
cysts)cysts)
 Bluntly roundedBluntly rounded
chromatoidal barschromatoidal bars
Cyst:10-20 μm

8. TransmissionTransmission
 HabitatHabitat Large intestines of manLarge intestines of man
 Cyst formCyst form
 With contaminated handsWith contaminated hands
 Contaminated water and foodContaminated water and food
 Incubation period: 8 days to several monthsIncubation period: 8 days to several months

9. Life CycleLife Cycle

10. PathologyPathology
 IntestinalIntestinal
 ExtraintestinalExtraintestinal

11. Entamoeba histolyticaEntamoeba histolytica
 Trophozoites colonize theTrophozoites colonize the
large intestine and invadelarge intestine and invade
the mucosa.the mucosa.

12. Entamoeba histolyticaEntamoeba histolytica PathologyPathology
1. A Primary Ulcer Can Occur.
Flask Shaped
Ulcers

13. Entamoeba histolyticaEntamoeba histolytica PathologyPathology
2. Extra-Intestinal
Lesions and Abscess
Occurs

14. Entamoeba histolyticaEntamoeba histolytica CystsCysts

15. DiagnosisDiagnosis
Stool Routine ExaminationStool Routine Examination::
 Loose stool mixed with blood (dark brown) andLoose stool mixed with blood (dark brown) and
mucusmucus
 Pus cellsPus cells ScantyScanty
 RBCsRBCs PresentPresent
 Charcoat – Leydon Crystals PresentCharcoat – Leydon Crystals Present
 Motile trophozoites and/or cystsMotile trophozoites and/or cysts - Present- Present

16. TreatmentTreatment
Metronidazole and related compounds act atMetronidazole and related compounds act at
both sitesboth sites