Makindo Medical Notes

🦠 Entamoeba dispar looks identical to Entamoeba histolytica but is non-pathogenic. Pathogenic amoebiasis is caused only by E. histolytica.

📖 About

• 💩 Amoebiasis is caused by the protozoan Entamoeba histolytica.
• 🍽️ Infection occurs via ingestion of food or water contaminated with cysts.

🔄 Transmission

• 🚰 Faecal–oral spread through contaminated food or water.
• ❤️ Oral–anal sexual contact can transmit cysts.
• 🪰 Insects may contaminate food with cysts.

🔬 Pathology

• 🟢 Cysts = infective stage; trophozoites = invasive stage.
• Ingested cysts release trophozoites in the small intestine → colon invasion → “flask-shaped ulcers.”
• Via portal vein, trophozoites may reach the liver → amoebic liver abscess.

🌍 Epidemiology

• 🌴 Prevalent in tropical & subtropical regions.
• 📑 Notifiable disease in many countries due to public health significance.

🩺 Clinical Features

• 🚽 Amoebic dysentery: bloody diarrhoea, abdominal pain, fever, weight loss. Complications → toxic megacolon, strictures, severe GI bleeding.
• ⚠️ Amoeboma: inflammatory mass (sigmoid/caecum) mimicking malignancy.
• 🩸 Amoebic liver abscess: fever, RUQ pain, tender hepatomegaly; risk of rupture → empyema, peritonitis, pericarditis.
• ❤️ Pericardial amoebiasis: due to ruptured liver abscess → chest pain, dyspnoea, hypotension.
• 🧠 Brain abscess: headache, fever, focal neurology (resembles pyogenic abscess).
• 🩹 Cutaneous amoebiasis: painful ulcers near anus or genitals.

🧪 Investigations

• 📉 FBC: anaemia, leukocytosis.
• 🧫 Serology: fluorescent antibody test positive in most liver disease cases.
• 🔍 Stool microscopy: motile trophozoites with ingested RBCs; cysts.
• 🧾 Colonic biopsy: flask-shaped ulcers ± strictures.
• 🩻 Chest X-ray: elevated right diaphragm, right pleural effusion (liver abscess complication).
• 🖥️ USS/CT abdomen: liver abscess (often right lobe), raised ALP possible.
• 🧠 CT/MRI head: for suspected brain abscess.

🔍 Differential Diagnosis

• 🩺 Inflammatory bowel disease.
• 🦠 Bacillary dysentery.
• 🐔 Salmonella infection.
• 💊 Pseudomembranous colitis.

🧾 Differential Diagnosis of Liver Abscess

• 🧫 Pyogenic abscess.
• 🐑 Hydatid cyst.
• 🎗️ Primary/secondary liver tumour.

💊 Management

• Metronidazole 800 mg PO TDS × 5 days → amoebic colitis.
• Metronidazole 400 mg PO TDS × 10–14 days → liver abscess, then Diloxanide 500 mg TDS × 10 days to eradicate cysts.
• 🪣 Liver aspiration if risk of rupture or poor response to therapy → “anchovy paste” aspirate.

🛡️ Prevention

• 🚱 Safe water: bottled/boiled in endemic areas.
• 🧼 Good hygiene and sanitation.
• ❌ No effective vaccine currently available.