Meet the parasite called Amebiasis.

What is amebiasis?

Amebiasis is a disease caused by a parasite, Entamoeba histolytica. It can be difficult to diagnose, because many parasites look similar to Entamoeba histolytica. Patients do not always show symptoms. If your doctor determines you are infected with amebiasis, medication is available.

Who is at risk for amebiasis?

Amebiasis is most common in people who live in tropical areas with poor sanitary conditions. However, anybody can get this disease. In the United States, it is most common in:

  • People who have traveled to tropical climates that have poor sanitary conditions.
  • Immigrants from tropical countries that have poor sanitary conditions.
  • People who live in institutions with poor sanitary conditions.
  • Men who have sex with men.

How can I become infected with E. histolytica?

E. histolytica can occur when a person:

  • Puts anything into their mouth that has touched the feces of an infected person.
  • Swallows something, such as water, that is infected with E. histolytica.
  • Swallows E. histolytica eggs from a contaminated surface.

What are the symptoms of amebiasis?

Only about 10%-20% of people who are infected with E. histolytica become sick. More severe forms of amebiasis are possible but very uncommon. In very rare cases, amebiasis may spread to the lungs or the brain. If you believe you have amebiasis, see your healthcare provider. Symptoms of amebiasis may include:

  • Loose stool
  • Stomach pain/cramping
  • Bloody stool
  • Fever
  • Abscess of the liver (collection of pus)

If I swallowed E. histolytica, how quickly would I become sick?

Symptoms usually develop within 2 to 4 weeks.

How is amebiasis diagnosed?

Your healthcare provider will ask you to submit a fecal sample. E. histolytica is not always found in the first sample, so multiple samples may be requested over a number of days.

Diagnosis of amebiasis can be difficult. Another ameba, Entamoeba dispar, is 10 times more common than E. histolytica, but the two amebae look the same under the microscope. E. dispar does not make people sick and does not need to be treated. Oftentimes, people are misdiagnosed with E. histolytica even though they are infected with E. dispar. Unfortunately, there are no tests to determine a difference between the two amebae, so it is best to assume you are infected with E. histolytica.  

A blood test may be required if your doctor believes the disease has spread to your intestine or another organ in your body. However, the blood test may not be helpful to diagnosis, because the blood test may come back positive if you’ve had amebiasis in the past, even if you are not infected now.

How is amebiasis treated?

Several treatments can be prescribed by a physician to treat amebiasis. If your E. histolytica infection has not made you sick, only one antibiotic is required. Two may be required if you are sick from the infection.

Safety tips for traveling to a country with poor sanitary conditions.

The following items are safe to drink:

  • Sealed, bottled water
  • Tap water that has been boiled at least 1 minute
  • Carbonated water from sealed containers
  • Carbonated drinks from sealed containers
  • Tap water filtered through an “absolute 1 micron or less” filter and dissolving chlorine, chlorine dioxide, or iodine tablets in the filtered water (available at camping/outdoor supply stores)

The following items may not be safe to drink:

  • Fountain drinks or drinks with ice cubes
  • Unpeeled, fresh fruits or vegetables
  • Unpasteurized dairy products
  • Food/drink sold by street vendors

How to prevent spreading amebiasis.

The risk of spreading amebiasis is low if the infected person practices good personal hygiene. To prevent spreading amebiasis, wash your hands after using the toilet, after changing diapers, and before and after handling or preparing food.

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