Amoebic liver abscess

What it is

Amoebic liver abscess is caused by Entamoeba histolytica, a protozoan parasite. Amebic dysentery is the most common presentation of the parasite, and liver abscesses are the most common extraintestinal one.

Causes and risk

It is transmitted through the faeco-oral route with the ingestion of viable protozoal cysts, so travel and contaminated food are part of the history.

Set against pyogenic liver abscess, the amoebic abscess falls in a lower age group, 20-40 rather than above 50; the ratio of men to women is above 10:1 rather than 1.5:1; it is solitary in 80% rather than 50%; and it follows travel in endemic areas, which the pyogenic one does not. Diabetes is uncommon with the amoebic abscess and more common with the pyogenic one, and jaundice too is uncommon with the amoebic abscess and common with the pyogenic one. Alcohol use is common with both, and both usually sit in the right lobe.

The pyogenic abscess, for contrast, is mostly secondary to infection originating in the abdomen: cholangitis due to stones or strictures is the commonest cause, followed by abdominal infection due to diverticulitis or appendicitis; in 15% of cases no cause can be found, and diabetes mellitus has been noted in 15% of adults with liver abscesses.