Amebiasis, also known as amoebic dysentery, is a serious parasitic infection. This condition can cause abdominal pain, diarrhea, and bloody stools, or it may cause no symptoms at all. The parasite that causes amebiasis only lives in humans and can spread through feces, infected food or water, or sexual contact.

Between 40,000–110,000 people die globally from amebiasis every year.

Practicing good oral hygiene can help prevent the spread of this infection. But if a person suspects they have amebiasis, they should contact their doctor as soon as possible. Early treatment can improve the outlook for this condition, as well as help stop it from spreading to other people.

This article will explain amebiasis and its causes. It will also discuss the risk factors and duration of this condition, as well as giving information on diagnosis, treatment, and prevention.

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Amebiasis happens due to infection from the amoebas of the Entamoeba group.

As a 2021 review explains, most symptomatic amebiasis infections involve the Entamoeba histolytica species. Entamoeba dispar, a different species in the Entamoeba group, cannot cause the disease. Scientists are unsure about whether Entamoeba moshkovskii can cause amebiasis.

Learn more about types of parasites here.

Around 9 out of 10 people with amebiasis do not experience any symptoms.

When amebiasis does cause symptoms, they result from the infection damaging a person’s intestines. These symptoms include:

The duration of a person’s amebiasis depends upon how the infection progresses. For example, the more common gastrointestinal symptoms gradually develop over 1–3 weeks after the infection has begun.

But some people can develop complications, such as amoebic liver abscesses, from amebiasis months or even years after coming into contact with Entamoeba histolytica. It will depend upon how well a person’s body is able to fight the infection.

The most common non-intestinal complication from amebiasis is amoebic liver abscesses. These can cause symptoms such as:

In rare cases, amebiasis can affect a person’s respiratory tract, for example, causing a collapsed lung. When some amoebic liver abscesses rupture, this can sometimes lead to conditions such as empyema or hepato-bronchial fistula. Their typical symptoms include:

It is even less common for amebiasis to cause heart problems, although this is possible.

Amebiasis can, in very rare cases, lead to amoebic brain abscesses. These can cause the following symptoms:

The parasite that causes amebiasis only lives in humans. If someone has amebiasis, they can spread it via their feces.

A person can get amebiasis by putting something in their mouth that has come into contact with the infected feces. If a person eats or drinks food or water that has touched the parasite, they may also become infected.

In the United States, amebiasis is more likely in people who have traveled to countries with poor sanitary conditions.

The parasite can also spread via oral-anal contact.

Infection explained

The majority of amebiasis infections happen following infection with Entamoeba histolytica amoebas.

As the Centers for Disease Control and Prevention (CDC) explain, when somebody has amebiasis, Entamoeba histolytica cysts can survive in that individual’s stool. The Entamoeba histolytica cyst-containing stool could then contaminate other people’s food, water, or body parts.

If these cysts reach a person’s small intestine, they can releaseparasites. These then move into the large intestine, where they multiply in number and produce more cysts. Some of these cysts and parasites will then pass into a person’s stool.

Of the parasites that remain in the large intestine, many will cause no symptoms. But if these parasites invade a person’s intestinal barrier, they may cause intestinal symptoms.

The parasites could also enter into a person’s bloodstream. From there, they could reach the respiratory tract, heart, or brain.

When a person’s amebiasis does not spread beyond the intestine, and the person receives early treatment, this condition will be fatal to fewer than 1% of individuals who have it.

Up to 90% of infections are asymptomatic. Among the 50 million who experience symptomatic amebiasis each year, 100,000 of them pass away.

Some people are more at risk of fatal amebiasis than others, including:

  • younger people
  • pregnant people
  • people using corticosteroids
  • people with cancer
  • malnourished people
  • people with alcoholism

A person should always seek treatment for amebiasis to help prevent the condition from worsening and to stop it spreading to other people.

Doctors will usually test samples of stool or other bodily fluids to confirm a diagnosis of amebiasis.

Doctors cannot solely rely on a person’s symptoms to make an accurate diagnosis. This is because amebiasis infections can have symptoms in common with many other conditions, including:

Because amebiasis can spread so easily, doctors recommend that everyone who has amebiasis receive treatment, even if they have an asymptomatic infection.

Medications that can treat amebiasis include:

  • nitroimidazoles, such as metronidazole
  • paromomycin
  • diloxanide furoate

In rare cases, such as when a person’s infection is very severe, doctors may also need to perform surgery.

The most important way to help prevent amebiasis is to practice good personal hygiene, including regular hand washing.

Some scientists believe that increases in regular hand washing could help prevent 50% of all worldwide deaths caused by diarrheal diseases such as amebiasis.

See a visual guide to proper hand washing here.

If someone travels to a country with poor sanitary conditions, they should be mindful of the food and drink they consume. Sealed bottled or canned water, boiled tap water, and carbonated water may be safe options.

People may wish to avoid some street food and raw, unpasteurized dairy products.

If a person has amebiasis, they should avoid sexual contact until the infection has gone.

Amebiasis happens when a person becomes infected with a type of parasite. It can cause symptoms such as diarrhea, abdominal pain, and bloody stools. Many people will not experience any symptoms from amebiasis. Sometimes, symptoms can take months or years to develop.

The parasite that causes amebiasis can spread through the feces of an infected person. Practicing good hygiene can help a person avoid this condition. This includes proper hand washing and being mindful of food and water sources.

If a person receives early treatment for amebiasis, the outlook is positive. Receiving treatment also helps stop the spread of the infection.