What Is Amebiasis?

What is amebiasis?

Amebiasis is a disease caused by a one-celled parasite called Entamoeba histolytica (ent-a-ME-ba his-to-LI-ti-ka).

Who is at risk for amebiasis?

Although anyone can have this disease, it is most common in people who live in developing countries that have poor sanitary conditions. In the United States, amebiasis is most often foundin immigrants from developing countries. It also is found in people who have traveled to developing countries and in people who live in institutions that have poor sanitary conditions. Men who have sex with men can become infected and can get sick from the infection, but they often do not have symptoms.

How can I become infected with E. histolytica?

• By putting anything into your mouth that has touched the stool of a person who is infected with E. histolytica.
• By swallowing something, such as water or food, that is contaminated with E. histolytica.
• By touching and bringing to your mouth cysts (eggs) picked up from surfaces that are contaminated with E. histolytica.

What are the symptoms of amebiasis

On average, about one in 10 people who are infected with E. histolytica becomes sick from the infection. The symptoms often are quite mild and can include loose stools, stomach pain, and stomach cramping. Amebic dysentery is a severe form of amebiasis associated with stomach pain, bloody stools, and fever. Rarely, E. histolytica invades the liver and forms an abscess. Even less commonly, it spreads to other parts of the body, such as the lungs or brain.

If I swallowed E. histolytica, how quickly would I become sick?

Usually 1 to 4 weeks later but sometimes more quickly or more slowly.

What should I do if I think I have amebiasis?

See your health care provider.

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 peopleare told that they are infected with E. histolytica even though they are not. Entamoeba histolytica and another amoeba, 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 needto 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.