AMOEBIC DYSENTERY
INTRODUCTION:
Dysentery is an acute inflammation of the large intestine characterized by diarrhoea with blood and mucus in the stools. It is usually caused by bacillary and amoebic infections.
PATHOGENESIS:
l. It results from the infection of the large intestine by Entamoeba histolytica.
2. After ingestion, the cyst undergoes further nuclear division and trophozoites are released. The trophozoites are carried to the large intestine where they produce the characteristic flask-shaped amoebic ulcerations.
3. Incubation period is 2-6 weeks.
4. A localized granuloma, presenting as a palpable mass in the rectum or causing a filling defect in the colon on radiography, is a common complication.
5. Amoebae may enter a portal venous radical and be carried to the liver where they multiply and produce an amoebic liver abscess.
DIAGNOSIS:
l. Stool examination: microscopic examination of a fresh sample of stool may demonstrate the motile trophozoites. They are about 30 microns in diameter, with a clear ectoplasm and a granular endoplasm, and usually contains red blood cell
2. Sigmoidoscopy: This may reveal the characteristic flask-shaped ulcers with normal surrounding mucosa, the aspirated material, or scrapings from the ulcer, or biopsy of the ulcer may demonstrate the trophozoites.
3. Amoebic serology: This can detect antibodies.
COMPLICATIONS:
l. Massive haemorrhage
2. Perforation and peritonitis
3. Toxic megacolon in fulminant cases
4. Post-dysenteric colitis
5. Amoebic liver abscess
6. Pleuropulmonary amoebiasis
7. Amoebic pericarditis
8. Cutaneous amoebiasis
CLINICAL FEATURES:
l. In amoebic dysentery, there is intermittent diarrhoea consisting of one to four, foul smelling, loose, watery stools which may contain mucus and blood.
2. Frequent flatulence and abdominal cramping.
3. Tender hepatomegaly and tenderness over the caecum, ascending colon and over left iliac fossa (Manson-Barr point).
TREATMENT:
l. Invasive intestinal amoebiasis is treated with metronidazole 800 mg thrice daily for 5 days or tinidazole 2 g daily as a single dose for three days.
2. After treatment, furamide should be given at a dose of 500 mg thrice daily for 10 days to eliminate luminal cysts, alternative agents include iodoquinol and paromomycin.
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