Amebic brain infection: granulomatous amebic encephalitis

[Cami]

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

• The amebas probably enter through the skin or lungs and spread to the brain through the bloodstream.
• Symptoms of granulomatous amebic encephalitis begin gradually and include confusion, headache, blurred vision, seizures, and skin sores.
• Imaging tests and a spinal tap can help doctors rule out other causes, and when a skin sore is present, a sample is taken and examined under a microscope to look for amebas.
• Doctors typically use a combination of drugs including miltefosine to treat the infection.

(See also Overview of Parasitic Infections.)

Free-living amebas are protozoa that live in soil or water and do not need to live in people or animals. Although they rarely cause human infection, certain types of these amebas can cause serious, life-threatening diseases.

The amebas that cause granulomatous amebic encephalitis live in water, soil, and dust throughout the world. Many people are exposed, but few are infected. Infection 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 differs from primary amebic meningoencephalitis. Primary amebic meningoencephalitis, though also rare, can affect healthy people who swim in fresh water. Primary amebic meningoencephalitis is caused by a free-living ameba called Naegleria fowleri, which enters the central nervous system through the nose.