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Granulomatous Amebic Encephalitis

By Richard D. Pearson, MD

Granulomatous amebic encephalitis is a rare, usually fatal infection of the central nervous system caused by Acanthamoeba species or Balamuthia mandrillaris. It usually occurs in people with a weakened immune system or generally poor health.

The amebas that cause this infection live in water, soil, and dust throughout the world. Many people are exposed, but few are infected. It usually occurs in people whose immune system is weakened or whose general health is poor, although Balamuthia mandrillaris may infect healthy people. Amebas probably enter through the skin or lungs and spread to the brain through the bloodstream.


Granulomatous amebic encephalitis symptoms begin gradually. Confusion, headache, and seizures are common. People may have a low-grade fever, blurred vision, changes in personality, and problems with speaking, coordination, or vision. One side of the body or face may become paralyzed. Balamuthia mandrillaris may cause skin sores. Most infected people die, usually 7 to 120 days after symptoms begin.


  • Computed tomography or magnetic resonance imaging

  • A spinal tap

  • Biopsy of skin sores

Computed tomography (CT) or magnetic resonance imaging (MRI) and a spinal tap (lumbar puncture) are usually done. These tests help exclude other possible causes but usually cannot confirm the diagnosis.

Skin sores typically contain amebas and, if present, are biopsied.

The diagnosis is often made only after death.


  • A combination of drugs

Doctors typically use a combination of drugs including

  • Miltefosine, which must be obtained from the Centers for Disease Control and Prevention (CDC)

and one or more of the following:

  • Pentamidine (an antifungal and antiprotozoal drug)

  • Sulfadiazine (an antibiotic)

  • Trimethoprim/sulfamethoxazole (an antibiotic)

  • Flucytosine (an antifungal drug)

  • Fluconazole or the related drugs voriconazole or itraconazole (antifungal drugs)

  • Amphotericin B (an antifungal drug)

Skin sores, if present, are cleaned and treated.

* This is the Consumer Version. *