بسم الله الرحمن الرحیم

بسم الله الرحمن الرحیم

Entamoeba gingivalis (non-pathogen) -Prevalance rate - Live site - Morphology - cytoplasm Diagnosis: may be mistaken for E.histolytica from a pulmonary abscess

Entamoeba coli (non-pathogen) Prevalance: 1 to 50% Morphology: trophozoite range 15-50µm ( very closely resemble E.histolytica) - cytoplasm - Pseudopodia Motility *nucleus *karyosome *peripheral chromatin

Entamoeba hartmani *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 : Iodamoeba butschlii : *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 *most common of the smaller intestinal amaeba *Size: trophpozoite and cyst is similar to theat of E.hartmani *Motility: sluggish pseudopodia extruded rapidly *Cytoplasm: Nucleus: contain large karyosome *Cyst:

Amebiasis (Amebic Dysentery) Causal agent: Entamoeba histolytica is well recognized as a pathogenic amoeba. 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. History: Loosh was first described in 1875

Morphology Different form of E. histolytica; 1- trophozoite 2- precyst 3- cyst(1, 2, 4 nuclei)

Trophozoite chractere 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 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 Prevalence of amebic infection varies with level of sanitation and generally higher in tropics and subtropics than in tempearate climates. *Worldwide prevalence is about 10% to 50% *Cyst passers are important source of infection 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 50,000-100,000 deaths each year.

Transmission methods of infections 1-driect contact of person to person( fecal-oral) 2- Veneral transmission among homosexual males( oral-anal 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 Effective factores: 1- strain virulence: - classic strain - non-classic strain; Laredo , Huff, …. - pathogen zymodemes 2- susceptibility of the host; nutrition status, immune-sys. 3- breakdown of immunologic barrier (tissue invasion)

Pathogenicity mechanisms 1- secreting proteolytic enzymes( histolysine ) and cytotoxic substances. 2 - contact-dependent cell killing 3 – cytophagocytosis Amebic killing target cell: 1- receptore-mediated adherence of amebae to target cell ( adherence lectin) 2- amebic cytolysis of target cell 3- amebic phagocytosis of killed target cell

Clinical symptoms Asymptomatic infection Symptomatic infection Intestinal Amebiasis Extraintestinal Amebiasis Dysenteric Non-Dysenteric colitis Hepatic Pulmonary The extra foci Liver abscces 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 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 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 furoate ( furamide) 500 mg 3 times daily / 10 days *Symptomatic amebiasis ( troph. & cyst): - Iodoquinol , 650 mg 3 times daily/ 20 days or Metronidazole (Flagyl) , 750 mg 3 times daily/ 10 days *Amebic colitis: Chloroquine, 250 mg 2 times daily * Acute amebic dysentery: Emetine hydrochloride, 1mg/kg daily IM or SC

Treatment 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,…..