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Acanthamoeba Infection FAQs

What is an Acanthamoeba infection?

Acanthamoeba is a microscopic, free-living ameba (single-celled living organism) commonly found in the environment that can cause rare, but severe, illness. Acanthamoeba causes three main types of illness involving the eye (Acanthamoeba keratitis), the brain and spinal cord (Granulomatous Encephalitis), and infections that can spread throughout the entire body (disseminated infection).

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Where is Acanthamoeba found?

Acanthamoeba is found worldwide. Most commonly, Acanthamoeba is found in soil, dust, fresh water sources (such as lakes, rivers, and hot springs), in brackish water (such as a marsh), and sea water. Acanthamoeba can also be found in swimming pools, hot tubs, drinking water systems (for example, slime layers in pipes and taps), as well as in heating, ventilating, and air conditioning (HVAC) systems and humidifiers.

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How does infection with Acanthamoeba occur?

Acanthamoeba keratitis infection has been linked to contact lens use, although people who do not use contact lenses can also become infected. Poor contact lens hygiene or wearing contact lenses during swimming, hot tub use, or showering may increase the risk of Acanthamoeba entering the eye and causing a serious infection. However, contact lens wearers who practice proper lens care can also develop infection.

Acanthamoeba can also cause disseminated infection by entering the skin through a cut, wound, or through the nostrils. Once inside the body, the amebas travel through the bloodstream to other parts of the body, especially the lungs, brain, and spinal cord.

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Can infection be spread from person to person?

The spread of Acanthamoeba infection from one person to another has never been reported.

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What are the symptoms of Acanthamoeba infection?

Acanthamoeba keratitis

The symptoms of Acanthamoeba keratitis can be very similar to the symptoms of other more common eye infections. The symptoms, which can last several weeks to months, are not the same for everyone and may include:

  • Eye pain
  • Eye redness
  • Blurred vision
  • Sensitivity to light
  • Sensation of something in the eye
  • Excessive tearing

Eye infection with Acanthamoeba has never been known to cause infections in other parts of the body.

Granulomatous Encephalitis

Acanthamoeba can cause a serious, most often deadly, infection of the brain and spinal cord called Granulomatous 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. Symptoms progress over several weeks and death usually occurs. Skin infections do not necessarily lead to disseminated disease.

Disseminated infection

Acanthamoeba can also cause skin lesions and/or disseminated infection. These infections usually occur in people with compromised immune systems.

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Who is at risk for infection with Acanthamoeba?

Acanthamoeba keratitis is most common in people who wear contact lenses, but anyone can develop the infection. For people who wear contact lenses, certain practices can increase the risk of getting Acanthamoeba keratitis:

  • Storage and handling lenses improperly
  • Disinfecting lenses improperly (such as using tap water or homemade solutions to clean the lenses)
  • Swimming, using a hot tub, or showering while wearing lenses
  • Coming into contact with contaminated water
  • Having a history of trauma to the cornea

disseminated infection caused by Acanthamoeba occurs more frequently in people with compromised immune systems or those who are chronically ill.

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Is there treatment for infection with Acanthamoeba?

Eye and skin infections caused by Acanthamoeba are usually treatable. It is important to see your health care provider immediately if you think you have Acanthamoeba infection of the eye or skin as medical treatment is most effective when started early.

Unfortunately, most cases of brain and spinal cord infection with Acanthamoeba (Granulomatous Encephalitis) are fatal.

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How can I prevent infection?

These guidelines should be followed by all contact lens users to help reduce the risk of eye infections, including Acanthamoeba keratitis:

  • Visit your eye care provider for regular eye examinations.
  • Wear and replace contact lenses according to the schedule prescribed by your eye care provider.
  • Remove contact lenses before any activity involving contact with water, including showering, using a hot tub, or swimming.
  • Wash hands with soap and water and dry before handling contact lenses.
  • Clean contact lenses according to instructions from your eye care provider and the manufacturer's guidelines.
    1. Never reuse or top off old solution. Use fresh cleaning or disinfecting solution each time lenses are cleaned and stored.
    2. Never use saline solution or rewetting drops to disinfect lenses. Neither solution is an effective or approved disinfectant.
    3. Be sure to clean, rub, and rinse your lenses each time you remove your lenses. Rubbing and rinsing your contact lenses will aid in removing harmful microbes and residues.
  • Store reusable lenses in the proper storage case.
    1. Storage cases should be rubbed and rinsed with sterile contact lens solution (never use tap water), emptied, and left open to dry after each use.
    2. Replace storage cases at least once every three months.

Contact lens users with questions regarding which solutions are best for them should consult their eye care providers. They should also consult their eye care providers if they have any of the following symptoms: eye pain or redness, blurred vision, sensitivity to light, sensation of something in the eye, or excessive tearing.


This information 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 parasites described above or think that you may have a parasitic infection, consult a health care provider.

 

A square ad showing an infected eyeball with Acanthamoeba. The caption reads, "Delayed diagnosis means poorer outcomes - think Acanthamoeba keratitis."

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  • Page last reviewed: November 2, 2010
  • Page last updated: August 21, 2012
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