2nd August 2023

Amoebiasis

The amoeboid protozoan Entamoeba histolytica causes mild diarrhoea, dysentery and colitis. It is mainly transmitted via the faecal-oral route and rarely, but increasingly through male-male sexual contact. It is an infection that occurs mainly in developing countries or returning travellers from low-income territories.

The majority of patients are asymptomatic or have self-limiting, mild diarrhoea. Severe amoebic dysentery and infectious colitis usually occur in immunocompromised individuals, extremes of age, and those with significant comorbidities. Severe infection presents after a long incubation period of up to 3 weeks with abdominal pain and severe, profuse bloody diarrhoea. Rarely it may present with life-threatening lower gastrointestinal bleeding.

Diagnosis is made through antigen testing or stool microscopy (the sample must be kept warm, termed as “hot stool”). Treatment is with metronidazole followed by paromomycin to prevent relapse. Asymptomatic patients are treated with paromomycin. Extraintestinal features mainly present as single or multiple liver abscesses and rarely as lung and brain abscesses.