Amebiasis

What is amebiasis?

Amebiasis is an intestinal illness caused by a microscopic parasite (amoeba) called Entamoeba histolytica. Approximately 50 cases are reported each year in Wisconsin.

Who gets amebiasis?

Anyone can get amebiasis, but it occurs more often in people arriving from tropical or subtropical areas, individuals in institutions for the developmentally disabled and homosexual males.

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 direct or indirect contact with fecal material from an infected person.

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 occasionally fever. In rare cases, 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 2 to 4 weeks.

For 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 source of the parasite. Fecal material from infected people may contaminate water or food and may serve as a vehicle to infect others. Animals are not infected with or carry the parasite, although, in some parts of the world, flies may serve to 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 parasites (amoeba) change from day to day.

What is the treatment for amebiasis?

Specific antibiotics can be prescribed by a doctor to treat amebiasis.

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, 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. Homosexual males should refrain from intimate contact until effectively treated.

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.