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Powerpoint Templates Page 1 Powerpoint Templates Gastro- intestinal tract Entamoeba histolytica Isna Indrawati

E hist 2013

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Page 1: E hist 2013

Powerpoint Templates Page 1Powerpoint Templates

Gastro-intestinal tract

Entamoeba histolytica

Isna Indrawati

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Class Rhizopoda

8 species live in GI tract : Entamoeba histolytica Entamoeba dispar Entamoeba coli Entamoeba gingivalis Entamoeba hartmani Endolimax nana Dientamoeba fragilis Iodamoeba butschlii

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• HOST : human amebiasis

•DISTRIBUTION:• cosmopolite, occurs worldwide

•>>> in tropic and sub tropic• strong correlation with personal hygiene

• high prevalence in countries where poor socioeconomic and sanitary conditions

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Prevalence of amebiasis• ± 50 million cases of invasive E.

histolytica disease occur each year (up to 100,000 deaths)

• Only an estimated 10%–20% of individuals infected with E. histolytica become symptomatic.

• Prevalence of symptomatic amebiasis vary geographically

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Prevalence (cont’d)

• Prevalence vary ranging from 1% to 21% in developing countries

• Indonesia : 10 – 18 %

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Morphology & Life cycle

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Pathogenesis

• the triad of Gal-lectin, cysteine proteinases and amoebapores of the parasite were thought to be responsible for invasive process

• Typical intestinal amebic ulcers : flask shape ulcer with slightly elevated areas of the mucosa

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Pathogenesis

Predilection site

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Clinical symptoms

• Incubation period : 2–4 weeks (but ranges from a few days to years)

• Most infections (≥90%) remain asymptomatic

• characterized classically by abdominal pain and bloody diarrhea.

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Clinical symptoms: Intestinal Amebiasis• Acute amebiasis ( 1 month):

– amebic dysentery, with frequent, urgent, small bloody stools, tenesmus

• Chronic amebiasis ( > 1 month):–alternating diarrhea and

constipation every few days– Fatigue, weight loss.

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Complications• Complications of intestinal

disease : spread through percontinuitatum):

rectovaginal fistulas, perianal skin ulceration, perforation, peritonitis, shock, and death.

hematogenous : extra intestinal amebiasis

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Extra intestinal amebiasis

• 1-3 monts after first attack : 5 % of intestinal amebiasis developed extra instestinal amebiasis

• trophozoites enter the bloodstream and disseminate to other body sites

• most common site: the liver (amebic liver abscess= ALA).

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• Amebic liver abscess presents with fever and right upper quadrant abdominal pain, hepatomegaly

• usually in the absence of diarrhea.

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Formation of ameboma

• Granulomatous reactions are pseudotumoural lesions, whose formation is associated with : necrosis, inflammation and oedema of the mucosa and submucosa of the colon.

• These granulomatous masses may obstruct the bowel (stricture)

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Diagnosis :• Detection of amoebic

trophozoites containing ingested red blood cells in the fresh faecal specimen

• Biopsy : identification of trophozoites within the tissues

• Detection of cysts ( light microscopy): should be reported as E. histolytica / E. dispar two species are indistinguishable

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trophozoites:

Trichrome stain

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E.hist/E.dispar in iodine

Chromatoid body with blunt rounded end

Trichrome stain

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Diagnostic support

• Colonoscopy • Aspiration of liver abscess • USG• Rx. Serology : high titres of

specific antibody is strongly correlated with the presence of invasive amoebiasis

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Diagnosis (cont’d)

• E. histolytica and E.dispar can be differentiated by :– Isoenzyme patterns : particularly

hexokinase.– Antigen detection: specific epitopes,

recognized by reaction with several monoclonal antibodies.

– DNA blotting : sequence differences in the rDNA

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Histopathology

Colon biopsy

Colonoscopy

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Epidemiology:• Transmission occurs through

ingestion of cysts from food or water contaminated by feces

• “Silent carrier” :–have the ameba in their

intestines and excrete amebic cysts, but have no symptoms.

– important as a source of infection

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Prevention :• drink purified or boiled water• Wash and peel all raw

vegetables and fruits before eating

• Protecting food from fly contamination

• Washing hands after defecation and before preparing or eating food

• using the toilet