Entamoeba histolytica is an intestinal dwelling parasite in the human gastrointestinal tract that can cause disease such as amebiasis, amebic colitis and amebic liver abscesses or or extraintestinal infections.

E.histolytica can colonise the gut of its host without causing any symptoms, however in approximately 10% of cases it becomes pathogenic and causes disease. Symptoms may include mild to bloody diarrhoea, abdominal pain, weight loss or fever. Infected individuals shed cysts in their faeces, which are then transmitted by the ingestion of contaminated food, water or from person-to-person contact.

The incubation period for E.histolytica is on average 2-4 weeks after exposure. The infectious period of an E.histolytica infection lasts as long as there are cysts excreted in the faeces of the infected individual. Therefore, the infectious period may last for weeks or many years if untreated.