Primary amebic meningoencephalitis caused by Naegleria fowleri, Karachi, Pakistan

Abstract

We report 13 cases of Naegleria fowleri primary amebic meningoencephalitis in persons in Karachi, Pakistan, who had no history of aquatic activities. Infection likely occurred through ablution with tap water. An increase in primary amebic meningoencephalitis cases may be attributed to rising temperatures, reduced levels of chlorine in potable water, or deteriorating water distribution systems. Primary amebic meningoencephalitis (PAM) is a fatal disease caused by the thermotolerant free-living ameba Naegleria fowleri. Found worldwide in moist soil and freshwater, these amebae proliferate during summer when ambient temperature increases. The organism enters the nasal cavity when water contaminated with amebae is aspirated. Subsequently, it invades the central nervous system through the olfactory neuroepithelium and causes a fatal infection that clinically resembles acute bacterial meningitis. We report 13 cases of N. fowleri PAM in a period of 17 months in the coastal city of Karachi, Pakistan.