Amebiasis is an intestinal illness caused by a microscopic parasite called Entamoeba histolytica. Anyone can get amebiasis, but it is recognized more often in people arriving from tropical or subtropical areas, individuals in institutions for the developmentally disabled and homosexual males.
Amebiasis is contracted by swallowing the cyst stage of the parasite in contaminated food or water.
People exposed to this parasite may experience mild or severe symptoms or no symptoms at all. Fortunately, most exposed people do not become seriously ill. The mild form of amebiasis includes nausea, loose stools, weight loss, abdominal tenderness and occasional fever. Rarely, the parasite will invade the body beyond the intestines and cause a more serious infection, such as a liver abscess. The symptoms may appear from a few days to a few months after exposure but usually within two to four weeks.