Free-living amoebae: Pathogens and the central nervous system (CNS) disease

Pathogenic free-living amoebae are known to be the causative agents of central nervous system infections leading to fatal primary amoebic meningoencephalitis or granulomatous amoebic encephalitis. While a higher risk of disease has been linked to impaired immunity in the case of pathogenic Acanthamoeba species, Balamuthia mandrillaris and Naegleria fowleri can cause infection in otherwise immunocompetent individuals. Although infections by pathogenic free-living amoebae are usually classified as infrequent, these free-living amoebae have been identified worldwide. Global warming coupled with the thermophilic nature of these amoebae, indicates that an increase in the cases of amoebic infections is to be expected. Herein, we describe the diagnosis, presentation, management and epidemiology of free-living amoebae infections.