Naegleria fowleri

Abstract

This chapter discusses Naegleria fowleri, basic microbiology, origin and taxonomy, metabolism and physiology, clinical features, pathogenicity and virulence, treatment, survival in the environment, methods of detection, epidemiology of waterborne outbreaks, and finally, risk assessment. Naegleria fowleri is an amoeboflagellate, free-living protozoan, found in aquatic and soil habitats. The life cycle consists of a motile, feeding trophozoite stage, non-feeding, non-replicating biflagellate stage and a resistant cyst stage. N. fowleri is acquired through exposure of the nasal passages to contaminated water. Inhalation of N. fowleri, trophozoites invade the brain through the nasal passages, typically causing primary amoebic meningoencephalitis (PAM), which is almost always fatal. Infection in humans occurs following inhalational exposure to biflagellates in recreational waters or cysts in soil or dust. Most cases have been linked to swimming in contaminated water. Furthermore, Chlorination inactivates Naegleria organisms. N. fowleri is sensitive to amphotericin B, but just a handful of survivors of PAM have been documented, usually because diagnosis comes too late.