Entamoeba histolytica infection (amoebiasis)
- Prevalence: 10% worldwide
- Asymptomatic cyst carriage in 90% cases
- Symptomatic cases per year: 50 million worldwide
- Fatalities per year: 100,000
- Transmission via fecal-oral route
- Results in enterocolitis
- Intraluminal disease
- Profuse Diarrhea with malabsorption
- Ulceration of colon and terminal ilium
- Intestinal bleeding
- Bowel Obstruction
- Intussusception
- Toxic Megacolon
- Pneumatosis coli
- Systemic dissemination
- Liver Abscess
- Lung Abscess
- Brain Abscess
- Intraluminal disease
Symptoms
- Acute
- Fulminant onset
- Cramping, moderate to severe Abdominal Pain
- Bloody, profuse Diarrhea
- Mucus in stools
- Tenesmus
- Malaise
- Chronic
- Normal stools alternate with symptomatic phase
Signs
- Acute
- Fever
- Diffuse abdominal tenderness
- Dehydration
- Weight loss
- Chronic
- Fever
- Tenderness and cramping of cecum and ascending colon
- Liver Abscess (within 5 months of onset)
- Fever (10-15 of cases)
- RUQ Abdominal Pain or liver tenderness
- Liver friction rub if Liver Abscess present
- Diarrhea (33% of cases)
Labs
- Entamoeba histolytica by stool PCR (preferred)
- Ova and Parasite exam (3 samples required)
- Liver Function Tests
- Fecal Leukocytes positive
- Occult blood positive
- Fecal Eosinophilia
Treatment
- Asymptomatic carriage of Entamoeba histolytica
- Treatment of asymptomatic carriage of Entamoeba histolytica (with a luminal agent only) is recommended to minimise transmission and the risk of developing invasive disease. Use:
- paromomycin 500 mg (child: 10 mg/kg up to 500 mg) orally, 8-hourly for 7 days – not registered for use in Australia but is available via the Special Access Scheme.
- Treatment of asymptomatic carriage of Entamoeba histolytica (with a luminal agent only) is recommended to minimise transmission and the risk of developing invasive disease. Use:
- Invasive amoebiasis
- For acute amoebic colitis (dysentery), use:
- tinidazole 2 g (child: 50 mg/kg up to 2 g) orally, daily for 3 days OR
- 2 metronidazole 600 mg (child: 15 mg/kg up to 600 mg) orally, 8-hourly for 7 days.
- For severe amoebic colitis (eg frequent blood-stained stools, perforation, peritonitis or toxic megacolon), use:
- 1 tinidazole 2 g (child: 50 mg/kg up to 2 g) orally, daily for 5 days OR
- 2 metronidazole 800 mg (child: 15 mg/kg up to 800 mg) orally, 8-hourly for 7 days OR (if the patient is unable to tolerate oral therapy)
- 2 metronidazole 750 mg (child: 15 mg/kg up to 750 mg) intravenously, 8-hourly for 7 days.
- For acute amoebic colitis (dysentery), use: