Entamoeba histolytica is one of the most common parasitic infections worldwide, infecting about 50 million people and resulting in 40 000–100 000 deaths a year. In Australia, people at risk of infection include immigrants, travellers returning from countries of high endemicity, Indigenous people, and men who have sex with men. Clinical manifestations range from asymptomatic carriage to invasive disease. Amoebic colitis and amoebic liver abscess are the most common invasive manifestations observed in Australia.
Nevertheless, cases of amebiasis are not restricted to these countries and are distributed worldwide, particularly in the tropics, most commonly in areas of poor sanitation. More than 50 million people worldwide are currently believed to be infected with Entamoeba histolytica. Most victims (90%) remain asymptomatic, while a varied array of clinical syndromes ranging from diarrhea, dysentery, and colitis to abscesses of the liver, spleen, and brain develop in the remaining 10%.
For symptomatic intestinal infection and extraintestinal disease, treatment with metronidazole or tinidazole should be followed by treatment with iodoquinol or paromomycin. Asymptomatic patients infected with E. histolytica should also be treated with iodoquinol or paromomycin, because they can infect others and because 4%–10% develop disease within a year if left untreated.