Amebiasis: Symptoms, Causes, and Treatment

What is Amebiasis?

Amebiasis is a parasitic infection of the intestines caused by the protozoan Entamoeba histolytica. Most people with amebiasis don’t experience major symptoms. Symptoms of amebiasis include stomach pain, loose stool, and abdominal cramping.

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Causes of Amebiasis

The protozoan, Entamoeba histolytica, or E. histolytica, usually gains access to the human body when a person consumes cysts (inactive form of the parasite that can live for several months in the soil or environment where they were deposited in feces), through contaminated food or water. It can also enter the body through direct contact with fecal matter. Food handlers may transmit the cysts while preparing or handling food.

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Microscopic cysts are present in soil, fertilizer, or water that’s been contaminated with infected feces. Apart from food or water, transmission is also possible during anal sex, oral-anal sex, and colonic irrigation.

When cysts enter the body, they lodge in the digestive tract. They then release an invasive, active form of the parasite called a trophozite. The parasites reproduce in the digestive tract and migrate to the large intestine where they burrow into the intestinal wall or the colon, leading to colitis, bloody diarrhea, and tissue destruction. The infected person can then spread the disease by releasing new cysts into the environment through infected feces.

Symptoms of Amebiasis

Symptoms of amebiasis begin to show about 1 to 4 weeks after consumption of the cysts. Symptoms at this stage tend to be slight and may include stomach cramping and loose stool.

The trophozites penetrates the intestinal walls and gain access to the bloodstream and travel to various internal organs such as the heart, lung, liver, brain, and other organs. These attack of trophozites on internal organs can lead to infections, severe illness, abscesses, and even death.

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If trophozites attacks the lining of your intestine, it can cause amebic dysentery. Amebic dysentery is a more dangerous form of amebiasis. Symptoms may include severe abdominal cramping, frequent watery and bloody stool.

Diagnosis of Amebiasis

Your doctor may asking about your recent health and travel history when he/she suspects amebiasis. A test may be performed to check for the presence of E. histolytica. You may have to give stool samples for several days to screen for the presence of cysts. Tests that may be conducted include:

  • Lab test to check for liver function: This helps determine if the ameba has destroyed your liver. The parasites may no longer show up in stool if they have spread outside the intestine.
  • Ultrasoundor CT scan: To check for lesions on your liver. If lesions appear, your doctor may need to perform a needle aspiration to see if the liver has any abscesses.
  • Colonoscopy:To check for the presence of the parasite in your large intestine (colon).

Who is at Risk for Amebiasis?

Amebiasis is common in tropical countries with underdeveloped sanitation such as Indian subcontinent, parts of Central and South America, and parts of Africa. It’s quite rare in the United States.

People with the greatest risk for amebiasis include:

  • people who have traveled to tropical locations where there’s poor sanitation
  • men who have sex with other men
  • immigrants from tropical countries with poor sanitary conditions
  • people who live in institutions with poor sanitary conditions
  • people with compromised immune systems and other health conditions

Treatments for Amebiasis

Treatment for mild cases of amebiasis generally consists of a 10-day course of metronidazole (Flagyl) in capsule form. Your doctor may also prescribe medication to control nausea if you need it.

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If the parasite is present in your intestinal tissues, the treatment must address not only the organism but also any damage to your infected organs. Surgery may be required if the colon or peritoneal tissues have holes.

Preventing Amebiasis

You need to practice proper sanitation if you must avoid amebiasis. Always wash your hands thoroughly with soap and water after using the bathroom and before handling food.

If you’re traveling to places where the infection is common, follow this regimen when preparing and eating food:

  • Wash fruits and vegetables properly before consuming.
  • Avoid milk, cheese, or other unpasteurized dairy products.
  • Stick to bottled water and soft drinks.
  • Avoid eating food sold by street vendors.
  • Avoid eating fruits or vegetables unless you wash and peel them yourself.
  • Boil water or treat it with iodine before consuming.


Disclaimer: The content provided on is purely informative and educational in nature and should not be interpreted as medical advice. Please use the content only in consultation with an appropriate certified medical doctor or healthcare professional.

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