Naegleria fowleri

Naegleria fowleri, also known as the brain-eating amoeba, is a species of the genus Naegleria. It belongs to the phylum Percolozoa and is classified as an amoeboflagellate excavate, an organism capable of behaving as both an amoeba and a flagellate. This free-living microorganism primarily feeds on bacteria, but can become pathogenic in humans, causing an extremely rare, sudden, severe, and almost always fatal brain infection known as primary amoebic meningoencephalitis (PAM), also known as naegleriasis.

It is typically found in warm freshwater bodies such as lakes, rivers, hot springs, warm water discharge from industrial or power plants, geothermal well water, and poorly maintained or minimally chlorinated swimming pools with residual chlorine levels under 0.5 g/m³, water heaters, soil, and pipes connected to tap water. It can exist in either an amoeboid or temporary flagellate stage.

Etymology

The organism was named after Malcolm Fowler, an Australian pathologist at Adelaide Children's Hospital, who was the first author of the original series of case reports (British Medical Journal, starting 1965) of PAM.

Life cycle

Naegleria fowleri, a thermophilic and free-living amoeba, is primarily found in warm and hot freshwater environments such as ponds, lakes, rivers, hot springs, and poorly maintained swimming pools. As temperatures rise, its population tends to increase. Although the amoeba was initially identified in Australia in the 1960s, it is believed to have evolved in the United States. N. fowleri exists in three forms - cyst, trophozoite (ameboid), and biflagellate. While it does not form cysts in solid human tissue, where only the amoeboid trophozoite stage is present, the flagellate form has been discovered in cerebrospinal fluid.