Brain-Eating Amoebas

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The headlines read more like the plot of a 50's era sci-fi horror movie than today's news: “Brain-Eating Amoeba Blamed in Teen's Death.” Is such a thing even possible? And shouldn't someone be calling out the National Guard?

First, let's get the High School Biology out of the way: amoebas are single-celled organisms that move and feed by using pseudopods. You may remember peeping through a microscope at Chaos carolinense and/or Amoeba proteus, which are the two most popular “teaching” amoebas. The brain-eater is called Naegleria fowleri and was discovered in 1965.

...And Naegleria is not coming after us, nor does it want our women. The brain eating that they do is all quite accidental.

Almost always, the creature gets into human bodies through our noses, often through the water we snort in when diving, water skiing, or doing other water sports. Once in the nose, they travel through the olfactory nerve into the frontal lobe of the brain -- which they will, indeed, use as their source of food. The condition of having your brain eaten by Naegleria fowleri is known as primary amoebic meningoencephalitis (PAM).

Although there are rarely more than 8 cases of PAM reported annually, scientists are uncertain whether the infection itself is as rare, with every infection ending in death, or whether infections are more common, undetected, and so not always fatal. 

Naegleria can be found in warm places around the globe, usually in:

  • Warm lakes, ponds, and rock pits
  • Mud puddles
  • Warm, slow-flowing rivers, especially those with low water levels
  • Untreated swimming pools and spas
  • Untreated well water or untreated municipal water
  • Hot springs and other geothermal water sources
  • Thermally polluted water, such as runoff from power plants
  • Aquariums
  • Soil, including indoor dust

Naegleria likes it hot, and can survive in water as hot as 113 degrees Fahrenheit. Note, however, that the creature cannot survive in either salt water or a properly treated swimming pool. Statistically, you're most likely to encounter it in the South, with over half of all infections having been reported in Texas and Florida.

The symptoms of PAM are very similar to those of viral meningitis, and include:

  • headache
  • fever
  • stiff neck
  • loss of appetite
  • vomiting
  • altered mental state
  • seizures
  • coma

In fact, there are instances of deaths that were attributed to meningitis which, after an autopsy, were chalked up to PAM.

 

There is currently no clear and quick way to diagnose PAM, and the prospects for successful treatment after such a diagnosis are equally sketchy. A number of drugs kill Naegleria amoebas in the test tube, but few patients survive PAM even when treated with these.