INTESTINAL (Protozoa) AND LIVER PARASITES
LOBOSEA Order: Amoebida

ENTAMOEBA HISTOLYTICA

his1-ic

Life cycle of Entamoeba histolytica: the disease has a world-wide distribution
with a higher prevalence in tropical and subtropical countries.
10% of the world population carries the protozoa.

hisc1-ic                hisc2-ic

E.histolytica: cysts with 4 visible nuclei. 
One cyst contains also elliptical chromidial body. 
The mature quadrinucleate cyst measures 8-15 µm in diameter. 
Stained fecal film. Wheatley modification of Gomori‘s trichrome technique. 
Objective 100 X

his2-ic

E.histolytica: diagnosis is based on morphological characteristics. 
Parasites can be observed
in wet mount preparations or in specimens stained with iodine or trichrome.
Preservation of stools with MIF or PVA is mandatory due
to rapid deterioration of trophozoites.

charcot

	Charcot-ic
	Charcot Leyden crystal in intestinal ameoebiasis

Intestinal ameobiasis: Charcot-Leyden crystal may be seen during amebic dyssentery.

Charcot Leyden crystal in intestinal ameoebiasis: Courtesy of Dottoressa Vittoria Fabbrizi e gruppo di Batteriologia ospedale Civile di Teramo, Italy.

his3-ic

E.histolytica trophozoite: size, shape, number of nuclei, karyosomal chromatin,
chromatoid bodies in cytoplasm are the characteristics used to identify
E.histolytica among other intestinal amoebae.
(Wet mount preparation).

hisc3-ic

E.histolytica: trophozoite of E.histolytica forma minuta. 10-20 µm in diameter. 
Stained fecal film. Wheatley modification of Gomori‘s trichrome technique. 
Objective 100 X

his4-ic

E.histolytica trophozoite: trophozoites exhibiting progressive,
directional motility by means of fingerlike pseudopodia,
can be observed in fresh stools.
Invasive trophozoites measure 20-60 µm in diameter.

hisc4-ic

E.histolytica: trophozoite of E.histolytica forma magna (dysenterica). 
10-20 µm in diameter, with ingested erythrocytes in the endoplasm. 
Stained fecal film. Wheatley modification of Gomori‘s trichrome technique. 
Objective 100 X

his5-ic

E.histolytica trophozoite: differential diagnosis from other intestinal
amoebae is based on size, shape, morphology of nuclei,
chromatin and karyosomal characteristics.
The characteristics of the single nucleus can be observed after iodine stain.

his6-ic

E.histolytica trophozoite: MIF preservation and concentration permits observation
of the characteristics of the single nucleus.

his7-ic

E.histolytica cyst: nuclei varies from 1 in immature cysts to 4,
the chromatin is uniformly distributed, the karyiosome is central and discrete.
A chromatoid body is usually present with rounded ends.

his8-ic	E_histolytica_2-ic

E.histolytica cyst: cysts measure 10-15 µm in diameter and are spherical.
(Iodine stain).

E_histolytica_2: E.histolytica cyst: cyst in faeces with one visible nucleus
with a central karyosome (Lugol stain).

his9-ic

E.histolytica trophozoite: the nucleus has a peripheral uniformly distributed
chromatin and a central located small karyosome.
Specific identification of the parasite is possible with permanent stains.
(Trichrome stain). 

his9-es-ic

Entamoeba histolytica: cyst, Gomori's trichrome (1.000 X)

his10-ic	E_histolytica1-ic

E.histolytica trophozoite: the cytoplasm contains fine granular matter;
erythrocytes and bacteria are occasionally seen.
Non invasive trophozoites measure 15-20 µm in diameter.
Differences from typical morphology are possible and frequent.

E_histolytica1: E.histolytica trophozoite: trophozoite (magna variety) in faeces.
Diameter approximately 30 mm. Nucleus with typical fine chromatin picture
(iron-hematoxylin stain).

his11-ic

E.histolytica colitis: the usual presentation of the disease is the amebic dyssentery.
Sigmoidoscopy may show typical ulcers.

his11a-ic

E.histolytica colitis: trophozoites can be observed at the bottom
of the lesions in tissue sections or in scraped material.
(Giemsa stain).

his12-ic

E.histolytica colitis: trophozoites can be identified by size,
shape and nuclei characteristics.
The severity of the disease may vary from mild colitis to dyssentery
with blood and mucus and to intestinal perforation.

his13.ic

E.histolytica: invasive trophozoites contain erythrocytes and bacteria (H&E stain).

his13mli40.ic	his13mli100.ic
his14mli40.ic	his14mli100.ic

his15mli4.ic	his15mli25.ic	his15mli40.ic	his15mli100.ic

his16mli10.ic	his16mli25.ic

his17mli100.ic

Amebic dyssentery observed in an italian tourist after a travel in Ivory Coast. 
The colonic mucosa is invaded by amoebae with lysis of inflammatory cells 
and tissue necrosis; progression of the invasion in the colonic mucosa usually 
leads the the formation of typical flask ulcers. 
In some cases ulcerations may extend to the submucosa causing microhaemorrhages 
and sometimes to the muscle layers and serosa leading perforation. 
Trophozoites within necrotic tissue, Images obtained with analogic CCD Camera 
and Zeiss Aristoplan Microscope.

his14-ic

E.histolytica colitis: trophozoites can be seen with other stains such as PAS.

his15-ic

E.histolytica, hepatic abscess: amebic trophozoites may
reach the liver via the portal vein.
Dissemination to lung, brain and skin may also take place.
Amoebae usually are not seen in aspirates and diagnosis
is possible by means of serologic tests.

 

 
INT...(Protozoa)LIVER....