Amebae can invade the central nervous system (CNS), causing rare but fatal infections. Seizures can complicate any of the ameba-caused clinical syndromes. Epidemiologic data are inadequate to comment on seizure incidence.

A few principal amebic parasites can cause CNS infection:


Amebic parasite Entamoeba histolytica Naegleria fowleri Acanthamoeba or Hartmannella
Geographic distribution Widespread distribution, tropics more virulent Southeastern United States Widespread
Host factors Nonspecific Freshwater swimming Chronic illness, immunosuppression
Clinical syndrome Entamoeba brain abscess (resembles brain abscess, tumor, chronic meningitis, or a combination of these) Primary amebic meningoencephalitis (acute meningoencephalitis) Granulomatous amebic encephalitis(resembles brain abscess, tumor, chronic meningitis, or a combination of these)
Signs/symptoms Meningitic symptoms
Focal signs
Acute meningitic symptoms
Subacute-chronic meningitic symptoms
Focal deficits
CSF findings increased protein
decreased glucose
increased protein
decreased glucose
Wet mount: motile trophozoites
increase protein
decreased glucose
Wet mount: sluggish organisms


CSF = cerebrospinal fluid; N = neutrophils; L = lymphocytes; WBC = white blood cell.

Table adapted from MJ Aminoff, DA Greenberg, RP Simon. Clinical Neurology. Stamford, CT: Appleton & Lange, 1996;37; and DT Durack. Amebic infections. In WM Scheld, RJ Whitley, DT Durack (eds), Infections of the Central Nervous System. Philadelphia: Lippincott–Raven, 1997;831–844.
Adapted from: Goldstein MA and Harden CL. Infectious states. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;83-133.
With permission from Elsevier (

Reviewed By: 
Steven C. Schachter, MD
Sunday, February 29, 2004