Climate change extends range of brain-eating amoeba

STORY BY Artem Kaznatcheev

Published: June 29, 2013

There are two things I really fear in life: people that don't listen to rational arguments and brain eating microbes. So you can imagine the nightmares I've been having after learning that climate change is allowing the brain eating Naegleria fowleri to spread further north than ever before in North America. These free-living eukaryotes spend their amoeboid stage swimming in warm water lakes and poorly chlorinated swimming pools. If even one of them finds its way inside your nasal passage and travels into your brain, then after a weeklong incubation period it will cause primary amebic meningoencephalitis (PAM) – in simpler terms: the little microbes will devour your cerebral fluid and gray matter, and with 98% certainty cause death.

PAM has been rare in the United States, killing an estimated three to eight people a year; historically confined to souther states like Texas and Arizona. Compare this to the closely related bacterial meningitis that affects around 9,500 Americans a year. For meningitis, a bactera (usually Neisseria meningitidis or Streptococcus pneumoniae in adults) enters the brain through the nasal cavity and causes similar symptoms to PAM – headaches, vomiting, and confusion – but also neck pain. However, unlike PAM, during meningitis it is not the microbes eating your brain that cause symptoms but your immune system's overly eager response. Meningitis is much more treatable if caught early, but the similarity in mechanism and symptoms can cause doctors to misdiagnose PAM as bacterlia meningitis and attempt incorrect treatments. In general, the low prevelance of PAM has made it difficult for doctors to study it.

But this might change with climate change causing unprecedented heat-waves in the midwest. The higher temperatures have allowed the habitabal zone of Naegleria fowleri to expand as far north as Minnesota. In 2010 and 2012, public health officials were stunned to find two cases in Lily Lake, Stillwater. This was 550 miles north of all previously reported infections. In the case of the 7-year-old girl in August of 2010, the air temperature near the the lake was 6.5F above average and the third highest since the start of records in 1891. An investigation by the Minnesota Department of Health concluded:

"Clinicians should be aware that N. fowleri-associated PAM can occur in areas at much higher latitude than previously described. Local weather patterns and long-term climate change could impact the frequency of PAM."

If super-storms, unprecidented drought and heat-waves, wildfires, and freak tornadoes are not enough to get you worried about climate change, then you now can add brain-eating amoeba to the list. Of course, maybe losing the part of your brain responsible for rational thought to a hungry microbe won't help you better understand the urgency of the situation.


For a longer discussion read this Verge article or the Minnesota Department of Health study.


Other Stories by Artem Kaznatcheev
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