Naegleria: another pathogenic ameba studies in germfree guinea pigs.

Free-living amebas of the genus Naegleria, of world-wide distribution and long considered harmless, have been linked etiologically with 57 fatal cases of primary amebic meningoencephalitis during the last decade. Naegleria from cultures derived from one of these fatal cases in Richmond, Virginia, have been inoculated intranasally, intraorally, into the conjunctival sac near the inner canthus of the eyes, and into induced skin lesions in adult germfree guinea pigs. Of 33 animals inoculated intranasally with 18 to 31 amebas, 31 developed a fatal encephalitis. There was considerable destruction of tissues of the cerebellum and the cerebrum and including the olfactory lobes. The meninges were involved to varying degrees in most of the animals. None of the animals inoculated by the three other routes developed either symptoms or lesions.