"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

March 29, 2010

March 29 - Naegleria fowleri

Naegleria fowleri is a protist that seems to be straight out of science fiction. Ranking at number five on the Science Channel’s "Top Ten Infectious Diseases", N. fowleri is a free-living amoeba capable of devouring your brain! This insidious creature makes its home as a flagellated amoeboid in characteristically warm freshwater sites such as lakes, rivers, geothermal hot springs, warm water discharge from industrial plants, poorly maintained and minimally-chlorinated or unchlorinated swimming pools and Jacuzzis. However, it has also been documented that it can be contracted by the inhalation of dust containing its cyst form, and has been isolated in places such as soil or air conditioning units. Although it prefers warm conditions that can reach up to 46°C, N. fowleri can endure winters by becoming cysts that settle into bottom-lying sediment. Capable of parasitizing a variety of mammals, including humans, the amoeba causes primary amebic meningoencephalitis (PAM), a fatal disease that has been recorded as the cause of death in over 150 worldwide cases reported. In all of these cases, the victim of this lethal microbe died within two to three days of infection. Infection occurs almost exclusively through the olfactory tract whereupon it migrates to the brain or spine of its host by traversing the olfactory nerve. It then feeds upon brain tissue and blood cells as an amoeboid trophozoite via phagocytosis and pinocytosis. Thankfully, it isn’t contagious between hosts.

Contributed by Jameson Clarke, Bucknell University.


  1. This is interesting and relevant to my interests.

  2. It changes its protein coat in response to being targeted by pretty much anything, including you're immune system, all the while it's feasting viciously on your brain's neurons.. sooo it's ninja-zombie amoeba that can rarely be exterminated from the body before it causes death? Touché, nature... touché.

  3. The diction and congruence of this article invokes a feeling of warmth I have seldom felt. Like an oven that's wide open, this essay is warm and golden. It is as if I have been sleeping all my life and I just awoke in a field of waffle sprouts and mango trees. The information of this piece deftly maneuvers through my brain with monster truck force while each gleaming fact shines like justice with a voice that is dark like tinted glass. It is the sort of bowel shaking earthquake that our society needs to steal our gaze from the one big sign; that double-wide shine on the boot-heels of our prime. Onion head hats aside, this is a wonderful piece of journalism

  4. It's kind of like horror movie, but on a much smaller scale. It would be bind of hard to film, even for a B-Movie, but creepy nonetheless. Thanks Jameson!

    I'm wondering how big a colony it would have created before it kills the host. How fast is the reproduction cycle once the cyst walls disappear?

  5. Bbbblluuuughgh. Perhaps the most unsettling parasites so far described here. [Shiver]

  6. Strange -- this is the first time I ever hear of N.fowleri as a parasite. The story I've heard and read in numerous sources (from protistologists) is that N.fowleri is rather an -opportunist-, just happening to tolerate the warmer temperatures of the human body (it's close relative, N.gruberi is less heat-tolerant and is not pathogenic) and treating it as yet another environment. In other words, Naegleria does not seek out a host, is not specialised for living inside one, nor does it require one for any life stage, and is there not actually a parasite.

    Also, one of the coolest features of this organism has been neglected: its remarkable ability to transform from a complete amoeba to a complete flagellate, going as far as de novo centriole/basal body assembly! (basal bodies are generally vertically inherited down cellular lineages). Lastly, it's (N.gruberi) genome has just been published, and it's wonderful news to cell biologists and those dealing with eukaryotic evolution as well.

    However, I do support a public outcry over this -- would encourage funding for this important candidate for a model organism due to its cell biology, despite the fact that N.fowleri infection is actually EXTREMELY rare. But shhh, protistology always deserves more funding! ;-)

  7. A 7 year old girl from Stillwater, MN just succumbed to N. fowleri:


  8. I love this article more than buttermilk