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New York State Department of Health
Communicable Disease Fact Sheet
Amebiasis
(amebic dysentery)

What is amebiasis?

Amebiasis is an intestinal illness caused by a microscopic parasite called Entamoeba histolytica. Approximately 500 cases are reported each year in New York State. Most of the cases occur in New York City residents.


Who gets amebiasis?

Anyone can get amebiasis, but it is recognized 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 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?

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.


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?

Specific antibiotics such as metronidazole 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 or children enrolled in day care 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. Homosexual males should refrain from intimate contact until effectively treated.


New York State Department of Health

Send questions or comments to: nyhealth@health.state.ny.us
Revised: February 1999