Amebiasis (amebic dysentery)

Last Reviewed: October 2011

What is amebiasis?

Amebiasis is an intestinal illness caused by a microscopic parasite called Entamoeba histolytica. Approximately 600 cases are reported each year in New York State.

Who gets amebiasis?

Anyone can get amebiasis, but it is recognized more often in people arriving from tropical or subtropical areas that have poor sanitary conditions, individuals living in institutions and people exposed to human feces through sexual contact.

How is amebiasis spread?

Amebiasis is contracted by consuming contaminated food or water containing the cyst stage of the parasite. 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.

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?

The parasite lives only in humans. Fecal material from infected people may contaminate water or food, which may spread the parasites to anyone who consumes them. Fecal material from infected people may also contaminate surfaces.

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 being passed in the stool, which varies from day to day, may be too low to detect from any single sample.

What is the treatment for amebiasis?

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

Should an infected person be excluded from work or school?

Although people with diarrhea due to amebiasis should not attend school or go to work, it is not necessary to exclude infected persons when they feel better and stools are normal. Casual contact at work or school is unlikely to transmit the disease. Special precautions may be needed by foodhandlers or children enrolled in daycare settings. Consult your local health department for advice in such instances.

What precautions should the infected person follow?

The most important precautions are careful handwashing after each toilet visit and proper disposal of sewage. People with amebiasis should refrain from sexual contact until the infection is treated and has cleared.