Infection of the central nervous system due to Acanthamoeba.

It is well established that Acanthamoeba castellanii, Acanthamoeba culbertsoni, Acanthamoeba polyphaga, and probably other species of free-living amebas are virulent opportunists capable of producing disease in humans and animals. Human infections involving brain, eyes, skin, and lungs have been reported from all continents. Central nervous system (CNS) infection due to Acanthamoeba species usually occurs in chronically ill, debilitated individuals, some of them receiving immunosuppressive therapy or taking broad-spectrum antibiotics. The disease runs a protracted, insidious clinical course and is known as granulomatous amebic encephalitis. Histopathologically, Acanthamoeba species may produce a multifocal, chronic, or subacute granulomatous encephalitis, with trophozoites and cysts present in CNS lesions. The portal of entry of the amebas into the CNS is probably the respiratory tract or a skin lesion, and the organisms reach the CNS by hematogenous spread. As of 1 January 1989, about 50 cases of granulomatous amebic encephalitis had been reported worldwide, 27 in the United States alone.