Amebiasis is an illness caused by infection with a microscopic parasite called Entamoeba histolytica . The illness can be mild or severe and it usually affects the intestines. Examination of feces under a microscope is the best way to diagnose amebiasis. Sometimes, several samples are examined because the number of parasites excreted in the feces can change from day to day. Amebiasis is also transmitted by sexual contact with an infected person.
Infected individuals are the only reservoirs for the parasite.
The symptoms of amebiasis vary with the individual. Some persons may become seriously ill while others have either mild or no symptoms. The mild form of amebiasis is characterized by nausea, diarrhea, weight loss, tenderness in the stomach region, and occasionally, fever. Some people with amebiasis may carry the parasite for periods lasting from several weeks to a year or more, often without any symptoms. In rare instances, the parasite can cause more serious infections, such as liver disease.