Transcript Entamoeba histolytica

‫بسم هللا الرحمن الرحیم‬
‫بسم هللا الرحمن الرحیم‬
Entamoeba gingivalis
(non-pathogen)
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-Prevalance rate
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- Live site
- Morphology
- cytoplasm
Diagnosis: may be mistaken for E.histolytica from a pulmonary abscess
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Entamoeba coli
(non-pathogen)
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Prevalance: 1 to 50%
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Morphology: trophozoite range 15-50µm
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( very closely resemble E.histolytica)
- cytoplasm
- Pseudopodia
Motility
*nucleus
*karyosome
*peripheral chromatin
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Entamoeba hartmani
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*small race of E.histolytica (morphologic similarity)
*size: trophozoite < 12 mμ , c yst < 10 mμ
*only clear-cut distinction between the two species is size
*trophozoite ingest bacteria but no RBC
Entamoeba dispare :
*There is no morphologic differences between this amoeba with E.histolytica
*This amoeba no ingest RBC
Iodamoeba butschlii :
*Trophozoite size(4-20μm), cytoplasm may be contain bacteria, large karyosome, small
granules
*Cyst size(9-10 μm): contain glycogen vacuole, sigle nuclei
Endolimax nana
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*most common of the smaller intestinal amaeba
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*Size: trophpozoite and cyst is similar to theat of E.hartmani
*Motility: sluggish
pseudopodia extruded rapidly
*Cytoplasm:
Nucleus: contain large karyosome
*Cyst:
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Amebiasis
(Amebic Dysentery)
Causal agent: Entamoeba histolytica is well recognized
as a pathogenic amoeba.
History: Loosh was first described in 1875
Geographic Distribution: Worldwide, with higher
incidence of amebiasis in developing countries.
In industrialized countries, risk groups include male
homosexuals, travelers and recent immigrants, and
institutionalized populations.
Morphology
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Different form of E. histolytica;
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1- trophozoite
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2- precyst
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3- cyst(1, 2, 4 nuclei)
Trophozoite chractere
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Size: 12-60μm in diameter;
Non-invasive form ( minuta) / E. dispare
Invasive form (magna) contain RBC, E. histolytica
Pseudopodia: quickly thrust out and vary in form; short, blunt, abroad, long,
figerlike
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Motility: actively motile , progressive , directional
Ectoplasm: is hyaline and distinguish from endoplasm
Endoplasm: is granular and may be contain ingested RBC
Nucleoplasm: contain a small centric or acentric karyosome with fine , uniform
granules of peripheral chromatin
invasive form
Non-invasive form
Different form of E.histolytica cyst
Life cycle
Life cycle
Epidemiology
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Prevalence of amebic infection varies with level of sanitation
and generally higher in tropics and subtropics than in
tempearate climates.
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*Worldwide prevalence is about 10% to 50%
*Cyst passers are important source of infection
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The true estimated prevalence of E. histolytica is close to 1%
worldwide.
Entamoeba histolytica is the second leading cause of
mortality due to parasitic disease in humans. (The first being
malaria). Amebiasis is the cause of an estimated 50,000100,000 deaths each year.
Transmission methods of infections
1-driect contact of person to person( fecal-oral)
2- Veneral transmission among homosexual males( oralanal
3- Food or drink contaminated with feces containing the
E.his. Cyst
4- Use of human feces (night soil) for soil fertilizer
5- contamination of foodstuffs by flies, and possibly
cockroaches
Pathogenesis
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Effective factores:
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1- strain virulence:
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- classic strain
- non-classic strain; Laredo , Huff, ….
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- pathogen zymodemes
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2- susceptibility of the host; nutrition status, immune-sys.
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3- breakdown of immunologic barrier (tissue invasion)
Pathogenicity mechanisms
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1- secreting proteolytic enzymes( histolysine )
and cytotoxic substances.
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2 - contact-dependent cell killing
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3 – cytophagocytosis
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Amebic killing target cell:
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1- receptore-mediated adherence of amebae to target cell ( adherence
lectin)
2- amebic cytolysis of target cell
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3- amebic phagocytosis of killed target cell
Clinical symptoms
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Asymptomatic infection
Symptomatic infection
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Intestinal Amebiasis
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Dysenteric
Non-Dysenteric colitis
Hepatic Pulmonary
Liver abscces
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Extraintestinal Amebiasis
The extra foci
Acut nonsupprative
Intestinal Amebiasis symptoms: Diarrhea or dysentery, abdominal pain, cramping , anorexia,
weight loss, chronic fatigue
Flask-like Ulcer
Extra-ntestinalAmebiasis
Pyogenic- Liver Abscess
Liver abscess
This is an amebic abscess of liver. Abscesses may arise in liver when there is seeding of
infection from the bowel, because the infectious agents are carried to the liver from the
portal venous circulation.
Laboratory Diagnosis
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Entamoeba histolytica must be differentiated from other
intestinal protozoa including: E. coli, E. hartmanni, E.
gingivalis,……
Microscopic identification of cysts and trophozoites in the stool
is the common method for diagnosing E. histolytica. This can
be accomplished using:
Fresh stool: wet mounts and permanently stained preparations
(e.g.,
trichrome).
Concentrates from fresh stool: wet mounts, with or without
iodine stain, and permanently stained preparations (e.g.,
trichrome).
Treatment
 Intestinal Amebiasis:
 *Asymptomatic amebiasis(cyst passer): Diloxanide
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furoate ( furamide)
500 mg 3 times daily / 10 days
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*Symptomatic amebiasis ( troph. & cyst): - Iodoquinol ,
650 mg 3 times daily/ 20 days or Metronidazole (Flagyl) , 750
mg 3 times daily/ 10 days
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*Amebic colitis: Chloroquine, 250 mg 2 times daily
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* Acute amebic dysentery: Emetine hydrochloride, 1mg/kg
daily IM or SC
Treatment
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Extraintestinal Amebiasis:
 *Amebic liver abscess, ameboma:
Metronidazole, as above plus dehydroemetine /
10 days or Metronidazole or dehydroemetine
as above plus Chloroquine , 500 mg 2 times
daily / 2 days,…..