Primary amoebic meningoencephalitis

As a serendipitous by-product of polio virus research, a highly fatal amoebic meningoencephalitis was recognized in animals. The causative microorganisms, contaminants of the viral cultures, were identified as small soil amoebae. These organisms, previously considered non-pathogenic, are prevalent throughout the world. Based on animal studies, the original investigators suggested the possibility of a similar disease in humans. Seven years later, human cases of amoebic meningoencephalitis were reported from widely separated areas of the world. Since 1965, a total of 79 cases have been reported. The literature of primary amoebic meningoencephalitis is presented. The history of the discovery and elucidation of this disease is reviewed. The 79 cases reported in the world literature are divided into two groups, those diagnosed retrospectively after reviewing previous deaths from meningoencephalitis, and those diagnosed at the time of the illness. The classification, morphology, pathogenicity, virulence and distribution of pathogenic soil amoebae are reviewed. The presenting clinical findings, diagnostic procedures, pathology, and management of this recently recognized, highly fatal, human disease is presented along with a report of a new case. Otolaryngologists should become familiar with this serious disorder with a transnasal portal of entry.