A common parasitic infection of the gastrointestinal system acquired through oral-faecal transmission

Causes

• The protozoan Entamoeba histolytica

Clinical features

It may present as:

Amoebic dysentery

• Persistent mucoid/bloody diarrhoea
• Abdominal pain
• Fever/chills

Amoebic abscess which can occur in one of the following forms as a result of spread via the blood stream:

• liver abscess - swelling/pain in the right sub-costal area
• brain - presenting as 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 - symptomless

Differential diagnosis

• Bacillary dysentery
• Any other cause of bloody diarrhoea
• Cancer of the liver
• Other causes of swelling in the liver

Investigations

Stool: microscopy for cysts and motile organisms

Management

Correct any dehydration (see p332)

metronidazole 800mg every 8 hrs for 8-10 days

HC2

child: 10mg/kg per dose

or tinidazole 2g daily for 3 days HC4

Chronic carriers (luminal) and tissue amoebiasis (liver, lung, brain, amoeboma)

metronidazole 800mg every 8 hours for 10 days

HC2

child: 10mg/kg per dose

or tinidazole 2g daily for 5 days

HC4

child: 50mg/kg per dose

Notes

metronidazole, tinidazole: contraindicated in pregnancy; avoid alcohol during treatment and for 48 hours after

metronidazole: take after food

Prevention

• Educate the public on personal and food hygiene (washing hands before eating), proper faecal disposal

• Ensure proper management of carriers

• Promote use of clean drinking water