Amebiasis

Causes and Risks:
The parasite can live in the large intestine without causing disease; or it can invade the colon wall causing colitis , acute dysentery, or chronic diarrhea . The infection may also spread through the blood to the liver and rarely, to the lungs, brain, or other organs. Amebiasis is present worldwide, but it is most common in tropical areas where crowded living conditions and poor sanitation exist. Africa, Latin America, Southeast Asia, and India have significant health problems associated with this disease. In the United States amebiasis is seen with increased frequency among homosexual males.

Transmission occurs through ingestion of cysts in fecally-contaminated food or water, use of human excrement as fertilizer, and person-to-person contact. Cockroaches and house flies can also spead the cysts . (There are an estimated 50 million cases worldwide of amebiasis with 40,000 to 50,000 deaths annually.)

Typical symptoms of intestinal amebiasis consist of frequent diarrheal bowel movements with cramps or colicky abdominal pain . Pain on defecation ( tenesmus ) is common. The diarrhea may contain blood or mucus. Uncomplicated attacks may last up to two weeks and recurrences are common unless the diagnosis is made and the individual is treated. Spread of the ameba into the wall of the colon may occur in 8 to 10% of cases and to the liver in approximately 1%.

Malnutrition and alcoholism predispose a person to more severe disease, as does immunosuppression . Recent travel to a tropical region is a risk factor. In the U.S., institutionalized mentally retarded people and male homosexuals are considered high risk groups.

Prevention:
When traveling in tropical countries where poor sanitation exists, drink purified or boiled water and do not eat uncooked vegetables or unpeeled fruit. Public health measures include water purification, water chlorination and sewage treatment programs.

Symptoms:
Mild symptoms:

Severe symptoms:

Note: In most people there are no symptoms.

Signs and Tests:
Examination of the abdomen may show liver enlargement .

Tests include:



Treatment:
The choice of drug depends on the severity of the infection. Several drugs may be indicated. Antiparasitic drugs such as metronidazole, idoquinol, or others may be used. Newer (investigational) drugs available include dehydroemetine (Mebadin) and diloxanide furoate (Furamide). When nausea or vomiting are present, intravenous therapy may be necessary until medications can be tolerated by mouth. Antidiarrheal medications are usually not prescribed.

Prognosis:
The death rate from untreated amebiasis is high, but the outcome is likely to be good with early treatment.

Complications:

  • liver abscess
  • medication side effects including nausea
  • spread of the ameba through the blood to the liver, lungs, brain, or other organs



Call Your Healthcare Provider:
Call for an appointment with your health care provider if persistent diarrhea is present.


Entamoeba species of ameba infest the intestinal system and can cause infection of the tissue outside of the intestinal tract. Here, the ameba have caused destruction and granulation of the anal area. (Courtesy of the Centers for Disease Control.)



Amebiasis, normally an infection of the intestinal tract, may spread and infect other organs such as the liver or brain. Infection of the brain can be fatal. In this slide, ameba are shown in a sample of brain tissue. Ameba represent a serious infection in immunocompromised individuals. (Courtesy of the Centers for Disease Control.)



This illustration shows the major organs of the digestive system. Their relative sizes and positioning in the body are also demonstrated.