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“Rare” Is Only Half the Amoeba Story . Do You Really Know The Rest? Sandra G. Gompf, MD Associate Professor, Department of Internal Medicine. “Rare” misses half the story….
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“Rare” Is Only Half the AmoebaStory Do You Really Know The Rest? Sandra G. Gompf, MD Associate Professor, Department of Internal Medicine
“Rare” misses half the story… As a parent, I often hear the probability of Primary Amoebic Meningitis (PAM) due to Naegleria fowleri is too low or “rare” to worry about. But it takes both probability and impact of an event to put risk into perspective. The impact of Naegleria infection is death. 100%. No replays. No do-overs.
“Rare” misses half the story… The probability of PAM is lower than Shark attacks Alligator attacks Lifetime risk for most people exposed to Naegleria is similar to Lightning But the impact of Naegleria fowleri is far deadlier. Your chance of surviving Ebola virus is better. And Naegleria is easy to prevent.
How many amoebae are in a lake? • Naegleria fowleri lives in all fresh bodies of water, all over the world. • In the summer, it is estimated that there are 10 to 1000 amoebae per liter of water in a fresh water lake. • The highest concentration associated with a human infection in FL has been 40 per liter. • It is very common. It preys on bacteria. • It has no intention of infecting us. But for reasons unknown, if they are forced into the nasal cavity, we can become a food source.
Death from PAM If you swim in a lake 10 times every year for 10 years in the summer, when Naegleria numbers are highest: Your risk of Naegleria infection is 0.0005 %. That’s close to your odds of being struck by lightning, but instead of 10% probability of death, PAM kills near-100%.
Compared to lightning, shark, & alligator deaths… *25-90% range • Lightning deaths • 1.4 per million U.S. population per year • Probability of dying after a lightning strike: 10 % • Odds of ever being struck by lightning: 0.0003 % • Shark deaths • 2.5 per million U.S. population • Probability of dying after a shark attack: 5 % • Alligator deaths • 2.5 per million U.S. population • Probability of dying after an alligator attack: 5 % • Even Ebola virus kills only 65% of its victims on average*!
GOOD NEWS!Just like lightning, sharks, & gators Protecting yourself from PAM in lakes, rivers, & hot springs is EASY: Keep your head above water. Avoid water forced up the nose. Wear nose clips if you’re diving, jumping, or dragged behind a boat. Be a good example for young kids.
The Florida Department of Public Health recommends that… Recreational water users should assume that there is always a low level of risk associated with entering all warm fresh water in southern tier states.
Ask yourself Would you stand in empty fields or near trees during lightning storms? Would you walk your small child near a lake where gators live? Would you swim in the ocean with a bleeding sore? Why would you dive or be pulled behind a boat in a lake without protecting your nose?
References http://aem.asm.org/content/67/7/2927.long http://srelherp.uga.edu/alligators/alligator-safety.htm http://www.shark.ch/Information/Accidents/index.html http://www.flmnh.ufl.edu/fish/Sharks/attacks/relarisk.htm http://www.statemaster.com/graph/hea_all_att_percap-health-alligator-attacks-per-capita Http://srelherp.uga.edu/alligators/alligator-safety.htm http://www.srh.noaa.gov/mlb/?n=lightning_stats#FLA ltg deaths/inj http://www.pbcgov.com/dem/sections/planning/business/lightning/facts.htm http://news.nationalgeographic.com/news/2004/06/0623_040623_lightningfacts.html