Naegleria fowleri is a protozoan in the taxonomic Family Vahlkamphidae, a microscopic organism that lives in soil, sewage, and warm water and very rarely causes parasitic disease in humans and animals. When it does, the illness is devastating. Parasitic disease caused by Naegleria fowleri is called primary amebic meningoencephalitis (PAM).
Life cycle of Naegleria fowleri
Naegleria fowleri, often referred to as simply “naegleria,” exists in nature in three forms: a flagellate, an amoeba, and a cyst. The flagellate stage, a small pear-shaped organism with two long whip-like flagellae at one end, is very mobile and is probably the stage that infects people who are exposed through water. Within the body, the flagellate converts to an amoeba, a slow moving single-celled organism that proliferates by dividing repeatedly. Returned to water, and occasionally in human spinal fluid, the amoeba will once again assume the flagellate form. The cyst stage, a tough spherical stage found only in the environment, forms when conditions are unfavorable for naegleria.
Primary amebic meningoencephalitis is a form of infectious meningitis—the organism grows in the brain and the meninges (the tissue membranes that surround the brain) -- that is almost always rapidly fatal. Most people who develop this parasitic disease have a fairly recent history of exposure to warm and possibly stagnant water: small lakes where the water gets very warm in summer, thermal pools, water heated by effluent from industrial processes, still warm reservoirs, etc. Naegleria fowleri usually enters the body when water is drawn in through the nose:
Avoid Naegleria fowleri and primary amebic meningoencephalitis
Parasitic disease caused by naegleria is very rare—only a few hundred cases have ever been reported—however a few common sense precautions will protect people from acquiring this and other water borne infections:
Cryptosporidium parvum - Parasite
Other interesting articles in Microbiology
Clinical Parasitology 9th ed. Beaver, Paul Chester, Rodney Clifton Jung, and Eddie Wayne Cupp. Philadelphia: Lea and Febiger, 1984.
Diagnostic Medical Parasitology 3rd ed. Garcia, Lynn S. and David A. Bruckner. Washington: ASM Press, 1997.
Foundations of Parasitology 6th Ed. Roberts, Larry S. and John Janovy Jr. Boston: McGraw Hill, 2000.