Introduction to Amoebiasis
Amoebiasis is common parasitic infection of the gastrointestinal system caused by the protozoan Entamoeba histolytica. It is acquired through faeco-oral transmission.
Clinical features of Amoebiasis
Amoebiasis may present as:
Amoebic dysentery
- Persistent mucoid/bloody diarrhoea
- Abdominal pain
- Fever/chills
Amoebic abscess
This can occur in any of the following forms as a result of spread via the blood stream:
- Liver abscess: swelling, pain in the right sub costal area
- Intracranial space-occupying lesion
- Lungs: cough and blood stained sputum
- Amoeboma: swelling anywhere in the abdomen
- Anal ulceration: may occur by direct extension from the intestinal infection
Chronic Carriers
- Symptom-free
Differential diagnoses of Amoebiasis
- Bacillary dysentery
- Any other cause of bloody diarrhoea
- Cancer of the liver
- Other causes of liver enlargement
Complications of Amoebiasis
- Rupture of abscess into the lungs, peritoneum,
- space-occupying lesion in the brain,
- right inguinal mass
Investigations
- Stool: microscopy for cysts and motile. organisms (amoebic dysentery)
- Full Blood Count
- Serology: amoebic precipitin (if available)
- Chest radiograph
- Abdominal ultrasound scan (in amoebic liver abscess)
Treatment objectives
- Rehydrate adequately
- Eradicate the protozoa
Drug treatment for Amoebiasis
Amoebic dysentery
- Correct dehydration
Metronidazole
Adult: 800 mg 8 hourly for 5 days
Child: 30 mg/kg/day in 3 divided doses for 5 days
Or
Tinidazole
Adult: 2g daily orally for 3 days (with food)
Child: 50-60mg/kg daily for 3 days
Amoebic liver abscess
Metronidazole
Adult: 800 mg 8 hourly for 10 days
Child:50mg/kg/day in 3 divided doses for 7 10 days
Tinidazole
Adult: 2 g daily orally for 3 days (with food)
Child: 50-60mg/kg daily for 5 days
Asymptomatic cyst carriers
Treat cyst carrier if the patient is a food handler with:
Diloxanide furoate
Adult: 500 mg every 8 hours for 10 days
Child: over 25 kg: 20 mg/kg orally every 8 hours for 10 days.
Child:
- under 25kg: ( I month – 12 years)- 6.6mg/kg every 8 hours for 8-10 days
- 12 years to 18 years: 500mg every 8 hours for 10 days
Non-drug treatment
- Aspiration is indicated to prevent spontaneous rupture of abscesses.
- Consult a surgeon.
Notable adverse drug reactions, caution
- Metronidazole is contraindicated in pregnancy.
- Avoid alcohol during and at least 48 hours after treatment because of disulfiram like reaction to metronidazole
Prevention of Amoebiasis
- Provision of safe drinking water
- sanitary disposal of faeces
- regular examination of food handlers and appropriate treatment where necessary.