Entamoeba Histolytica: Clinical Manifestations

Primary or intestinal lesions:

• Primary infection of this parasite is limited entirely to the large intestine.

1. Amoebic dysentery:

• Parasite presence and activity of in  wall of large intestine

 Amebiasis most frequently involves :

• the cecum and ascending colon
• followed in order by the sigmoid, rectum, and appendix.
• Causes amoebic dysentery characterised by frequent passage of stool and griping pam.
• The contain mucus and occasionally blood.

2. Amoebic ulcers:

• Multiple ulcers in the caecum, ascending colon and rectum.
• In advanced cases, haemorrhage due to erosion of blood vessels.
•  The ulcerative lesions develop undermining of margins of the ulcer due to lytic action of the trophozoites.
• Ulcer has a flask shaped with a narrow neck and broad base.

3. In acute case :

• Perforation and gangrene of intestinal
• Pericolic abscesses & peritonitis 

Metastatic or secondary lessions:

• Enter into the blood circulation
• Reaches the different parts of the body
• Cause extra intestinal or metastatic lesion.
• It is also known as “tissue amoebiasis”.

1.Amoebic liver abscess :

• May be single large abscess or multiple, and may involve both lobes.
• In the tropics 2-10% of the individuals infected with E. histolytica suffer from hepatic complications

Common in :

• Most common in right lobe liver/right posterior-superior region 
• Portal vein is in direct continuation with the right tributary.
• Pus in amoebic liver abscess is not due to suppuration, but is a mixture of sloughed liver tissue and blood
•  Pus is chocolate coloured, classically called anchovy-sauce
• Abscess wall good for culture

Complications

• Pleuropulmonary infection is the most common complication.
• Cardiac involvement results following the rupture of an abscess involving the left lobe of the liver.
• Associated with very high mortality.
• Intraperitoneal rupture occurs in 2-7% of patients.
•  Left lobe abscesses are more likely to progress to rupture because of their later clinical presentation

2. Pulmonary amoebiasis:

• Appearance of single or multiple abscesses in one or both lungs.
• An amoebic lung abscess is almost always secondary to spread from the liver.

3. Cerebral amoebiasis:

• Appearance of small absess in one of the cerebral hemisphere.

4. Splenic amoebiasis:

• Rare
• Cause abscess.

5. Cutaneous amoebiasis:

• Skin lesions
• Skin is involved directly over the region adjoining a visceral lesion
• Extensive necrosis and sloughing of the skin and subcutaneous tissues are caused by the trophozoites of E. histolytica
• Granulomatous ulceration and granulomatous mass may occur in the peri-anal region.

6. Urinogenital tract Infection:

• Rare
• Cause amoebic ulcer of the penis and vaginitis.

• The main reservoir for entamoeba histolytica is man

Mode of Transmission: 

1. Faecal-oral route
2. Oral-rectal contact
3. Transmission through vectors ( flies, cockroaches and rodents)

Cutaneous amoebiasis

• Direct infection from liver
• Granulomatous ulceration and granulomatous mass may occur in the peri-anal region.

Characteristic feature of amoebic ulcer

• Flask shaped
• Undermined edge

Amoebic liver abscess :

• In the tropics 2-10% of the individuals infected with E. histolytica suffer from hepatic complications
• Liver abscess is the most common extra-intestinal manifestation of amoebiasis.

Common in :

• Most common in right lobe liver/right posterior-superior region 
• Portal vein is in direct continuation with the right tributary.
• Pus in amoebic liver abscess is not due to suppuration, but is a mixture of sloughed liver tissue and blood
• Pus is chocolate coloured, classically called anchovy-sauce
• Abscess wall good for culture
• Pleuropulmonary infection is the most common complication.
• Most common cause of amoebic lung abscess is direct spread from liver
• Amoebic liver abscess ruptures most commonly into pleural cavity