Dysentry is an infective disease of the large bowels characterized by frequent passing of blood and mucus with stool along with several abdominal cramps. Various microbial and chemical causes can result into dysentery in humans.   Among the microbial aetiology are included both protozoa and bacteria.

Dysentery caused by protozoa is called amoebic dysentery and dysentry caused by bacteria is called bacillary dysentery.


Both amoebic and bacillary dysentery resemble each other, but can be differentiated on aetiological, clinical and laboratory grounds. Followings are the differences between amoebic dysentery and bacillary dysentery :

Differences in Pathology

FeaturesAmoebic DysenteryBacillary Dysentery
Causative agentEntomoeba histolyticaShigella species, Enterohemorrhagic E. coli, Vibrio parahemolyticus, Campylobacter jejuni
Nature of lesionNecrotic due to proteolytic fermentSuppurative due to diffusible toxins
Depth of ulcerUsually deepShallow
Margin of ulcerRagged and underminedUniform, clear-cut (sharp)
Intervening mucosNormalInflamed
Type of necrosis (cellular level)Pyknotic (pyknotic body and mouse eaten cells)Karyolysis (ghost cell and ring nucleus)
Liver abscessCommonRare
Cellular responseMononuclearPolymorphonuclear

Differences in Clinical Features

FeaturesAmoebic DysenteryBacillary Dysentery
Abdominal tendernessLocalizedGeneralized

Differences in Macroscopic Features of Stool

FeaturesAmoebic DysenteryBacillary Dysentery
Number6-8 motions per dayOver 10 motions per day
AmountRelatively copiousSmall
ColorDark redBright red
NatureBlood and mucus mixed with fecesBlood and mucus, no feces

Differences in Microscopic Features of Stool

FeaturesAmoebic DysenteryBacillary Dysentery
RBCIn clumps, reddish yellow in colorDiscrete or in rouleaux, bright red in color
Pus cellsScantyNumerous
MacrophagesVery fewLarge and numerous, many of them contain RBCs, hence mistaken for E. histolytica
Pyknotic bodiesVery commonNil
Ghost cellNilNumerous
ParasitesTrophozoites of E. histolyticaNil
BacteriaMany, motileScanty, non-motile
Charcot-leyden crystalsPresentNil


  1. Great. Awsomelly interesting. Thanks very much. Coming back to what you said at the level of ” DIFFERENCE IN PATHOLOGY ” : cellular response; does it mean that in amoebic dysentery polymorphonuclear are absent? I remember the once said eosinophiles ( a polymorphonuclear cell ) fights against parasitic infections and is from them that Charcot Leyden crystal originates. Mononuclear such as macrophages and lymphocytes are mostly present in bacillary infections. so, I think level…………………. To be corrected. To confirm what I am saying, go to DIFFERENCES IN MICROSCOPIC FEATURES YOU WROTE.

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