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

Who gets 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 found in 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 is this parasite spread?

Amebiasis is contracted by swallowing the cyst stage of the parasite in contaminated food or water. It can also be spread by person-to-person contact.

What are the symptoms of amebiasis?

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.

How soon after exposure do symptoms appear?

The symptoms may appear from a few days to a few months after exposure but usually within two to four weeks.

How long can an infected person carry this parasite?

Some people with amebiasis may carry the parasite for weeks to years, often without symptoms.

Where are the parasites that cause amebiasis found?

Infected people are the only sources of the parasite. Fecal material from infected people may contaminate water or food which may serve as a vehicle to infect others. Animals are not infected with and do not carry the parasite. Flies, in some parts of the world, may transfer cysts from human stool to fruits and vegetables.

How is it diagnosed?

Examination of stools under a microscope is the most common way for a doctor to diagnose amebiasis. Sometimes, several stool samples must be obtained because the number of amoeba changes from day to day.

What is the treatment for amebiasis?

Several antibiotics are available to treat amebiasis. Treatment must be prescribed by a physician. You will be treated with only one antibiotic if your E. histolytica infection has not made you sick. You probably will be treated with two antibiotics (first one and then the other) if your infection has made you sick.

Should an infected person be excluded from work or school?

Generally, it is not necessary to exclude an infected person from work or school. Casual contact at work or school is unlikely to transmit the disease. Special precautions may be needed by foodhandlers or children enrolled in day care settings, or individuals in institutions for the developmentally disabled. Consult your local health department for advice in such instances.

What precautions should the infected person follow?

The most important precaution is careful handwashing before eating or preparing food and after each toilet visit. Proper disposal of sewage is also important. Infected persons should refrain from oral-genital contact until effectively treated.

Where can I get more information?

UTAH DEPARTMENT OF HEALTH
OFFICE OF EPIDEMIOLOGY
July 2003