Naegleria /nɛˈɡlɪəriə/ is a genus consisting of 47 described species of protozoa often found in warm aquatic environments as well as soil habitats worldwide.

[4] Naegleria is found worldwide in typically aerobic warm aquatic environments (freshwater such as lakes and rivers) and soil habitats.

[5] The few species that are pathogenic seem to be characteristically thermophilic, preferring warmer temperatures such as nuclear power plant cooling water.

[6] One species, Naegleria fowleri, can be an opportunistic and usually fatal pathogen of humans if it enters the depths of the nasal cavity.

[10] The cyst contains usually 2-8 pores (often depending on the species) and is formed when conditions become adverse, such as residing in non optimal temperature.

[10] When adverse conditions are restored to normal, the organism can escape the cyst through the pores in its amoeboid form.

[2] Therefore, this flagellated stage is transient and the organism usually reverts to the amoeboid form within an hour, with transformation taking about 100 minutes.

[5] The mitochondrial genome clearly encodes for aerobic respiration which is seen through its ability to perform oxidative phosphorylation and use oxygen as a terminal electron acceptor.

[5] Remarkably the organism's genome also encodes for an elaborate anaerobic metabolism such as substrate-level phosphorylation and an ability to use fumarate as the terminal electron acceptor.

[5] This anaerobic system is hypothesized to be used in slightly anoxic muddy environments during the cyst life stage.

[5] The genus Naegleria’s ribosomal DNA (rDNA) consists of an extrachromosomal plasmid of which about 4000 exist in each cell.

[13] There it destroys neurons and causes primary amoebic meningoencephalitis (PAM), a very rare, yet fatal disease.

[7] N. fowleri possess secreted proteases, phospholipases, and pore-forming peptides which are characteristics of a pathogenic process.

[14] They have been observed to cause central nervous system (CNS) infections in animals such as mice, rats, squirrels, guinea pigs, sheep, as well as the gills of fish.

[1] Another practical importance of the genus is that it is extensively studied for its transformation from the amoeboid phase into the flagellated stage, which can be difficult to induce in other genera.