Acanthamoeba. Unlike cases of amebic meningoencephalitis due to Naegleria, the evolution was subacute, and cerebrospinal fluid lymphocytosis was an important feature. The patient had contact with contaminated water 2 weeks before the onset of symptoms. Although the precise portal of entry is unknown, evidence suggests a hematogenous spread in spite of the lack of a primary focus. The pathological process was characterized by a necrotizing, granulomatous encephalitis with predilection for the temporal lobes, deep gray masses, and brain stem. The information on this infection has been reviewed, and the clinical and pathological differences between infection caused by Naegleria and that produced by Acanthamoeba are discussed.