Amebic Meningitis / Encephalitis Infections FAQs

Balamuthia mandrillaris is a free-living ameba (a single-celled living organism) found in the environment. It is one of the causes of granulomatous amebic encephalitis (GAE), a serious infection of the brain and spinal cord. 

Scientists at the Centers for Disease Control and Prevention (CDC) first discovered Balamuthia mandrillaris in 1986. The ameba was found in the brain of a dead mandrill baboon. After extensive research, B. mandrillaris was declared a new species of ameba in 1993. Since then, more than 200 cases of Balamuthia infection have been diagnosed worldwide, with at least 70 cases reported in the United States.

Balamuthia has been found in dust and soil in many places around the world. It is possible that Balamuthia may also live in water.

Balamuthia infection is not spread from person to person.

Balamuthia is thought to enter the body when soil containing Balamuthia comes in contact with skin wounds and cuts, or when dust containing Balamuthia is breathed in or gets in the mouth. Once inside the body, the amebas can travel through the blood stream to the brain, where they cause GAE. There are also a few reports of dogs that might have become infected after swimming in ponds.

Balamuthia infection can occur at any time of year.

The symptoms of Balamuthia infection can begin with a skin wound on the face, chest, torso, arms, or legs. If the infection involves the brain, the disease it causes is called granulomatous amebic encephalitis (GAE). Diagnosis of Balamuthia GAE can be difficult, but some early symptoms might include:

• Headaches
• Stiff neck or head and neck pain with neck movement
• Sensitivity to light
• Nausea
• Vomiting
• Lethargy (tiredness)
• Low-grade fever

Other signs of Balamuthia GAE might include:

• Behavioral changes
• Seizures
• Weight loss
• Partial paralysis
• Difficulty speaking in full sentences
• Difficulty walking

The disease might appear mild at first but can become more severe over weeks to several months. Often the disease is fatal, with a death rate of more than 89%. Overall, the outlook for people who get this disease is poor, although early diagnosis and treatment may increase the chances for survival.

It can take weeks to months to develop the first symptoms of Balamuthia GAE after initial exposure to the amebas.

GAE is chronic and symptoms develop over a period of several weeks to as long as 2 years. Although Balamuthia GAE is often fatal, there are several recorded cases of Balamuthia infection where the patients survived after long-term treatment with multiple drugs. In some of those cases, the patients were able to return to normal, functioning lives.

Balamuthia can infect anyone; this includes persons that are healthy or persons with weakened immune systems (such as persons with HIV/AIDS, cancer, liver disease, diabetes mellitus and/or persons taking immunosuppressive drugs following organ transplantation).

Contact your healthcare provider as soon as possible if you think you may have a Balamuthia infection.

Doctors and scientists must use special research tests to identify Balamuthia. These tests are not widely available, but CDC is available to help with testing.

Currently, treatment recommendations include the use of a combination of several drugs. Most cases of Balamuthia are diagnosed right before death or after the patient has died. This delay in diagnosis limits the amount of experience doctors have using different drugs to treat Balamuthia infection. Current treatment plans are based on lab studies of the ameba and the few cases where the patients have survived.

Currently, there are no known ways to prevent infection with Balamuthia since it is unclear how and why some people become infected while others do not. Research is currently underway to learn more about Balamuthia in hopes of finding ways to prevent future infections.

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 Aeratitis), the brain and spinal cord (Granulomatous Encephalitis), and infections that can spread throughout the entire body (disseminated infection).

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.

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.

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.

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.

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.

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.

Sappinia is a free-living ameba (a single-celled living organism) found in the environment. There are two known species of Sappinia: Sappinia diploidea and Sappinia pedata. This ameba causes amebic encephalitis, which is an infection of the brain. This infection is similar to those caused by other free-living amebas, such as Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba. Only one case of amebic encephalitis due to Sappinia infection has been reported worldwide. In 1998, a healthy 38-year-old man from Texas was diagnosed with an infection caused by Sappinia diploidea. Recently, however, this infection was reidentified as being caused by Sappinia pedata. Although the patient was hospitalized, he survived without any long-term consequences.

Sappinia can be found around the world. It is usually found in:

• Elk and buffalo feces
• Places where farm animals are known to eat
• Soil containing rotting plants
• Fresh water sources

It is believed that the person in Texas who became ill with amebic encephalitis due to Sappinia was infected through contact with animal feces on his farm in Texas.

It is thought that Sappinia may enter the body through the nose or via cuts and bruises on the body. In the only known case, the patient had signs of a sinus infection before developing symptoms of amebic encephalitis.

There are no reported cases of the spread of Sappinia spreading from one person to another. All free-living amebas can live and multiply in the open environment without entering a human or animal host.

Symptoms of a Sappinia infection include:

• Headache
• Sensitivity to light
• Nausea or upset stomach
• Vomiting
• Blurry vision
• Loss of consciousness

A scan of the one infected patient’s brain also revealed a 2-centimeter tumor-like mass on the back left section of his brain.

Treatment for the one identified case of Sappinia infection included the removal of a tumor in the brain and a series of drugs given to the patient after surgery. This treatment lead to the patient’s full recovery.

Upon examination of the tumor tissue samples, scientists at the Centers for Disease Control and Prevention (CDC) determined that the species of free-living ameba that caused the infection was Sappinia.

Sappinia can infect anyone. However, individuals with weakened immune systems and people who have contact with animal feces (poop) are at a higher risk for infection. A weakened immune system may be the result of AIDS, cancer, liver disease, diabetes mellitus, or drugs used after an organ transplant.

It is likely that most cases of Sappinia infection are not reported because the ameba is hard to identify.

Infections that involve the brain can be fatal and are often diagnosed late in the disease process; however, amebic encephalitis due to Sappinia was not fatal in the only patient identified so far.