Acanthamoeba Infection Factsheet

What is an Acanthamoeba infection?

Acanthamoeba are microscopic ameba commonly found in the environment. Several species of Acanthamoeba have been found to infect humans, A. culbertsoni, A. polyphaga, A. castellanii,
A. healyi, (A. astronyxis), A. hatchetti, A. rhysodes, and possibly others.

Where are Acanthamoeba found?

Acanthamoeba spp. (spp. means several species) are found worldwide. Most commonly, Acanthamoeba are found in the soil and dust, in fresh water sources such as lakes, rivers, and hot
springs and in hot tubs. Acanthamoeba may also be found in brackish water and in sea water. Amebas can also be found in Heating, Venting, and Air Conditioner units (HVAC), humidifiers,
dialysis units, and contact lens paraphernalia.

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Acanthamoeba have been found in the nose and throat of healthy people as well as those with compromised immune systems.

How does infection with Acanthamoeba occur?

Acanthamoeba can enter the skin through a cut, wound, or through the nostrils. Once inside the body, amebas can travel to the lungs and through the bloodstream to other parts of the body, especially the central nervous system (brain and spinal cord).

Through improper storage, handling, and disinfection of contact lenses, Acanthamoeba can enter the eye and cause a serious infection.

What are the signs and symptoms of Acanthamoeba infection?

There are several ways Acanthamoeba spp. can affect the body.

Each year, many people are infected with Acanthamoeba. Eye infections result from contact lens cases becoming contaminated after improper cleaning and handling. Risk of Acanthamoeba
infection is higher for people who make their own contact lens cleaning solution. Acanthamoeba enter the eye via contact lenses or through a corneal cut or sore. Infection or a corneal ulcer results.

In addition, Acanthamoeba spp. can cause skin lesions and/or a systemic (whole body) infection. Acanthamoeba spp. cause a serious, most often deadly infection called granulomatous amebic
encephalitis (GAE). Once infected, a person may suffer with headaches, stiff neck, nausea and vomiting, tiredness, confusion, lack of attention to people and surroundings, loss of balance and
bodily control, seizures, and hallucinations. Signs and symptoms progresses over several weeks; death generally occurs.

Who is at risk for infection with Acanthamoeba?

Infections caused by Acanthamoeba spp. occur more frequently in people with compromised immune systems or those who are chronically ill.

Is there treatment for infection with Acanthamoeba?

Yes. Eye and skin infections are generally treatable. Although most cases of brain (CNS) infection with Acanthamoeba have been fatal, a few however, have recovered from the infection
with proper treatment. Acanthamoeba infections of the brain (CNS) are almost always fatal.

Can infection be spread from person to person?

No cases have ever been reported.
How can I prevent an infection with Acanthamoeba?

Eye infections may be prevented by using commercially prepared contact lens cleaning solution rather than making and using home-made solutions. There is little that can be done to prevent skin and body infection.
For more information:

1. Centers for Disease Control. Acanthamoeba keratitis associated with contact lenses-United States.
MMWR 1986:35: 405-8.
2. Centers for Disease Control. Acanthamoeba keratitis associated with soft contact lens wearers-United States. MMWR 1987; 36:397-8, 403-4.
3. Ma P, Visvesvara GS, Martinez AJ, Theodore FH, Daggett PM, Sawyer TK. Naegleria and Acanthamoeba infections: Review. Rev Infect Dis 1990; 12:490-513.
4. Visvesvara GS, Stehr-Green JK. Epidemiology of free-living ameba infections. J Protozool 1990; 37:25S-33S.
5. Martinez AJ, Visvesvara GS. Free-living, amphizoic and opportunistic amebas. Brain Pathol 1997; 7:583-598.

This fact sheet is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health care provider. If you have any questions about the disease described above or think that you may have a parasitic infection, consult a health care provider.