Acanthamoeba infection

Acanthamoeba is a microscopic, free-living ameba, or amoeba (single-celled living organism), that can cause rare, but severe infections of the eye, skin, and central nervous system. The ameba is found worldwide in the environment in water and soil. The ameba can be spread to the eyes through contact lens use, cuts, or skin wounds or by being inhaled into the lungs. Most people will be exposed to Acanthamoeba during their lifetime, but very few will become sick from this exposure. The three diseases caused by Acanthamoeba are:

Acanthamoeba pathology

Acanthamoeba keratitis – An infection of the eye that typically occurs in healthy persons and can result in permanent visual impairment or blindness.

Granulomatous Amebic Encephalitis (GAE) – A serious infection of the brain and spinal cord that typically occurs in persons with a compromised immune system.

Disseminated infection – A widespread infection that can affect the skin, sinuses, lungs, and other organs independently or in combination. It is also more common in persons with a compromised immune system.

Distribution

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.

Link to contact lens use

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.

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

Symptoms of 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

Disseminated infection

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.

Skin lesions

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

Precautions

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.

Treatment

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.

Prevention

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.
• Never reuse or top off old solution. Use fresh cleaning or disinfecting solution each time lenses are cleaned and stored.
• Never use saline solution or rewetting drops to disinfect lenses. Neither solution is an effective or approved disinfectant.
• 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.
• 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.
• 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.

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