Entamoeba are protozoan parasites and have a direct life cycle. In reptiles, species of this genus can cause unspecific clinical signs like diarrhea, anorexia and lethargy. Most commonly affected organs include the liver and intestine. An infection can cause severe inflammation with necrosis and abscesses. Systemic distribution in other organs is also possible. Peracute mortalities have also been described. Entamoeba invadens is the most important pathogenic species in reptiles. An infection with clinical signs is most often found in snakes and carnivorous lizards, but clinical disease has also been described in a wide variety of chelonian species. Asymptomatic carriers have been described, especially among herbivorous tortoises, but these animals can also develop clinical disease. Therefore, E. invadens should be considered pathogenic for all reptiles.
This protozoan is transmitted by the fecal-oral route, by ingestion of infectious cysts. Diagnostic testing can be carried out by PCR and histopathology from the affected tissues, as well as from faeces, or by microscopic examination from faeces. Repeated examinations might be necessary due to the changing or low amount of excretion.