AMEBIASIS.ppt

7/28/2019 AMEBIASIS.ppt

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AMEBIASIS

Infection caused by Entamoebahystolytica

90 % cases are asymptomatic First described by Lsch (1875) from a

patient in Leningrad and discovered atrophozoit form

Quinche & Roos (1893) discovered a cystform Walker & Sellards proved that E,

hystolytica caused amebic colitis


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ETIOLOGY

Entamoeba hystolytica(pathogen ) &Entamoeba dispar(apathogen)

E. hystolytica :Trophozoit : hystolytica & minuta20-40 um (12-50 um), roundnucleus, endoplasma (food vacuoles

RBC, phagocytized elements), clearectoplasmaCyst : 10-20 um, oval or round, 1 4 nuclei


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Entamoeba hystolytica

LIFE CYCLE ..(1)Infective cyst is ingested the wall isdigested in small intestines released of

4 quadrinucleat ameba.Passed into large intestine to grow anddivide by binary fision to formtrophozoites

Trophozoites live in the lumen and mucosalcrypt of the large bowel (caecum,descending colon, recto-sigmoid)


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Entamoebahystolytica

LIFE CYCLE ..(2)Invasion of mucosa and passage viabloodstream may occur colitis, liver

abscessIn the absent of diarrhea, trophozoitesround up and encyst in the lumen oflarge intestines (never in the tissue)passed in the faeces

Within few hours cysts are infected


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EPIDEMIOLOGY

Worldwide , tropical regionInfect 10 % of world population

Third cause of death among parasiticdiseases (schistosomiasis, malaria)Relevent factors in transmission : fecaldisposal, water-borne infections, food

handlers, personal hygiene, arthropodes asmechanical vectors.Humans are the principal reservoir


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PATHOGENESIS

Trophozoites in the intestinal lumenDepletion of intestinal mucus, diffuse

inflammation, disruption of the epithelialbarrierAttach to the interglandular epithelMicroulceration of the mucosa (cecum

sigmoid colon, rectum)Submucosal extension of ulceration flask shaped ulcer


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CLINICAL MANIFESTATION .. (1)

Asymptomatic cyst passage

intestinal amebiasis fulminant

diseaseAsymptomatic cyst passage

most common type

persistent state

symptomatic form


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CLINICAL MANIFESTATION (2)

Symptomatic amebic colitisdevelops 2-6 weeks after ingestion

of infected cystlower abdominal pain, mild diarrhea

malaise, weight loss full blown

dysentriaestool : little fecal material, blood,mucus


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CLINICAL MANIFESTATION .(3)

Toxic megacolonfulminant intestinal infection

high fever, profused diarrhea, severeabdominal pain, severe boweldilatation with intramural air

children, geriatric, steroidChronic amebic colitisuncommon, mimic IBS


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Ameboma (amebic granuloma)excessive production of granulation

tissuececum, rectosigmoidpresent as an irregular tumorpain, palpable mass, obstructive

symptoms, haemorrhage


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Amebic liver abscesspreceded by intestinal colonization

trophozoites invade vein through portalsystemsliver parenchyma is replaced by

necrotic materials anchovy paste)

surrounded by a thin rim ofcongested liver tissueameba may be found near the capsule of

the abscess


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CLINICAL MANIFESTATION ..(6)

Amebic liver abscessfebrile, right upper quadrant abdominal

pain radiate to the shoulder, hepato-megaly, weight losselevated right dome of diaphragm on

chest X ray

complication : rupture amebic empyema,peritonitis, pericarditis, cardiactamponade


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CLINICAL MANIFESTATION ..(7)

Other form of extraintestinalamebiasis

- Cutaneus and genital amebiasis- Pleuropulmonary amebiasis- Brain abscess


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DIAGNOSIS (1)

AnamnesisPhysical diagnosis

Laboratory- Stool : E. hystolytica)(trophozoite)- Culture

- Serology : counterimmunodiffusion,agar gel diffusion, ELISA (6-12 mo neg), IHA (up to 10 yrs)


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DIAGNOSIS .(2)

Amebic liver abscess:Chest X-ray, liver scan, ultrasono-

graphy, MRIRadiographic barium harmful inacute amebic colitis.Endoscopy + biopsy in ameboma


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DIFFERENTIAL DIAGNOSIS

Bacterial diarrhoea caused byCampylobacter, enteroinvasive Esche-

richia coli, Shigella sp, Salmonella sp,Vibrio sp.Pyogenic liver abscess : older patient,

underlying bowel disease, surgery


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TREATMENT..(1)

Luminal amebicides- Poorly absorbed

- High concentration in the bowel- Limited to cyst & trophozoites close

to mucosa- Iodoquinol, Diloxanide furoate,Paromomycin


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TREATMENT..(2)

Tissue amebicides- High concentration in blood and

tissue- Metronidazole, Tinidazole, Ornida-

zoleAspiration of liver abscess- Diagnostic

- Failure to respond clinically in 3-5 days.- To threat of imminent rupture- To prevent left lobe liver abscess rupture


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PREVENTION

Adequate sanitationEradication of cyst carriage

Disinfection by iodination (tetragly-cine hydroperiodide)

No effective chemoprophylaxis

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AMEBIASIS.ppt