Entamoeba is a genus of Amoebozoa found as internal parasites or commensals of animals.
Several species are found in humans and animals. Entamoeba histolytica is the pathogen responsible for invasive ‘amoebiasis’ (which includes amoebic dysentery and amoebic liver abscesses). Others such as Entamoeba coli (not to be confused with Escherichia coli) and Entamoeba dispar are harmless. With the exception of Entamoeba gingivalis, which lives in the mouth, and E. moshkovskii, which is frequently isolated from river and lake sediments, all Entamoeba species are found in the intestines of the animals they infect. Entamoeba invadens is a species that can cause a disease similar to E. histolytica but in reptiles. In contrast to other species, E. invadens forms cysts in vitro in the absence of bacteria and is used as a model system to study this aspect of the life cycle. Many other species of Entamoeba have been described, and it is likely that many others remain to be found.