How is amebiasis diagnosed?

Your health care provider will ask you to submit stool samples. Because E. histolytica is not always found in every stool sample, you may be asked to submit several stool samples from several different days.

Diagnosis of amebiasis can be very difficult. One problem is that other parasites and cells can look very similar to E. histolytica when seen under a microscope. Therefore, sometimes people
are told that they are infected with E. histolytica even though they are not. Entamoeba histolytica and another ameba, Entamoeba dispar, which is about 10 times more common, look the same when seen under a microscope. Unlike infection with
E. histolytica, which sometimes makes people sick, infection with E. dispar never makes people sick and therefore does not need
to be treated. 

If you have been told that you are infected with E. histolytica but you are feeling fine, you might be infected with E. dispar instead. Unfortunately, most laboratories do not yet have the tests that can tell whether a person is infected with E. histolytica or with E. dispar. Until these tests become more widely available, it usually is best to assume that the parasite is E. histolytica.

A blood test is also available. However, the test is recommended only when your health care provider thinks that your infection has invaded the wall of the intestine (gut) or some other organ of your body, such as the liver. One problem is that the blood test may still be positive if you had amebiasis in the past, even if you are no longer infected now.