Naegleria fowleri: Brain Eating Amoeba
Charles P. Davis, MD, PhD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR
Yes, there are things that can eat your brain: the Naegleria fowleri story.
So far this summer, three people have died from Naegleria fowleri, termed the "brain-eating amoeba." Naegleria fowleri is the genus and species name of an ameboflagellate that causes primary amebic meningoencephalitis (PAM) in humans, mainly in children and young adults. It exists in three forms, free-living cysts, trophozoites, and flagellated forms. Its life cycle is mainly in the cyst to trophozoite to cyst cycle (see image) and resembles other amoeboid genera like Acanthamoeba. The organism was discovered in Australia in 1965 by Drs. M. Fowler and R. Carter but probably has been occasionally infecting humans for centuries.
Fortunately, humans are rarely infected with Naegleria fowleri. Most doctors do not ever see or diagnosis this infection in any of their patients. Although the organisms can be found worldwide, mainly in warm waters (lakes, rivers, hot springs, power plant warm water discharge pools) that have loose sediment, are stagnant or contaminated with stirred up bottom sediment, or even in poorly chlorinated swimming pools, only about 121 cases have occurred in the US according to the CDC. Only one person has reportedly survived a diagnosed case of primary amebic meningoencephalitis caused by this parasite.