Skip to main content

Brain-Eating Amoeba: Naegleria fowleri in the U.S.

Holle is a retired English and creative writing teacher who writes on a variety of topics.

Naegleria fowleri lives in warm freshwater lakes, ponds, rivers, and streams.

Naegleria fowleri lives in warm freshwater lakes, ponds, rivers, and streams.


Have you ever heard of Naegleria fowleri? I’ve heard of it before, but I never really paid much attention to the ameba until now. We’re about to head to Florida for a summer vacation, and the grandkids will be going with us. I’m not usually careful enough when it comes to my own safety, but with the grandkids, I can be somewhat of a safety stickler. If you’re a grandparent, I’m sure you can relate.

Anyway, Naegleria fowleri is pretty widespread in the Sunshine State, even though infections caused by the ameba are rare. When they do occur, however, they’re almost always fatal. Information like that can certainly make a concerned grandparent or parent sit up and pay attention. I’ve always believed that knowledge is power, so I’ve been studying this brain-eating amoeba, finding out as much about it as I could. One problem with this is that scientists don’t really know a lot about Naegleria fowleri or how to treat primary amoebic meningoencephalitis, and in my opinion, that makes the amoeba even scarier. I mean, when the experts don’t even fully understand a topic in their field of study, how is the average person supposed to understand it and take the proper safety precautions?

In this article, I’m sharing with you what I’ve learned about Naegleria fowleri, along with a few travel tips and other safety tips.


Let’s begin with a little information about amoeba, in general. I’ll start with the spelling of the term. When I was in school, we spelled it amoeba. Now, however, it seems that in the United States, the proper spelling among many scientists is ameba. In the UK, it’s still amoeba. I don’t know . . . maybe the grade schools I attended in South Georgia just preferred the UK spelling.

Anyway, an amoeba is a one-celled organism with an irregular shape. The plural of amoeba is amoebae, and the plural form of ameba is amebas or amoebae. This gets rather confusing, doesn’t it? Amoebae live in water or in some other fluid, and in soil. The amoeba has a cell nucleus—sometimes more than one. The cytoplasm, the jelly-like inside of the cell, is surrounded by the cell membrane. The fluid within the cell of the amoeba is controlled by a contractile vacuole, and food is stored in food vacuoles. Amoebae are capable of movement, by using “false feet,” called “pseudopods.” To move, one of the false feet is stretched out, and the rest of the cell changes shape in order to follow. Food is obtained in a similar fashion. When the amoeba finds a particle of food, the cell surrounds it and devours it. Amoebae eat bacteria, along with algae and other types of phytoplankton. To reproduce, amoebae use nuclear division or mitosis.

Amoebae can be harmful to humans and animals when the tiny organisms enter the body. Across the globe, tens of thousands of human deaths are caused by amoebae each year. When swallowed, the organisms can cause damage to the intestines, the liver, and other organs. When the amoebae enter the host through the nose, they can damage the brain, as is the case with the brain-eating amoeba, Naegleria fowleri.

Naegleria fowleri is a brain eating amoeba.

Naegleria fowleri is a brain eating amoeba.

Brain Eating Amoeba

A brain-eating amoeba?? That sounds sort of like a good name for a low-budget horror film, doesn’t it? Unfortunately, however, it’s all too real.

The term used to describe this condition is primary amoebic meningoencephalitis, or PAM, for short. How does this happen? Believe it or not, the amoebae, Naegleria fowleri, don’t cause destruction of brain tissue when swallowed. Instead, the danger occurs when they enter the victim’s nose. From there, they travel to the brain via the olfactory nerve, which leads to the brain’s frontal lobe. The brain is a great environment for the invading amoebae, where they find moisture, warm temperatures, shelter, and food.

Once there, the amoebae don’t find their usual food source, bacteria, so they feed on brain tissue, instead. They use enzymes to dissolve brain tissue, turning it into a food source. They make a small opening in the brain cells and feed on the escaping contents.

Naegleria fowleri

Naegleria fowleri is often referred to as a brain-eating amoeba. It lives in warm freshwater bodies of water, including ponds, lakes, and untreated swimming pools, along with damp soil. Some scientists once thought that it could survive only in stagnant water, but that’s been proven false. It’s also been found in rivers and in natural springs. Some scientists have also speculated that the amoebae live only in the silt on the bottom of a body of water, but it’s been found in every level of the water column, although it is usually more prevalent in the silt. Another incorrect assumption is that Naegleria fowleri can live only in very warm climates. In the United States, this would include the southernmost states. Here’s a news flash: the amoeba has been found as far north as Minnesota. It is, however, more common in southern states where summers get extremely warm, including Florida and Texas.

Naegleria fowleri are microscopic, about ¼ the size of a human hair’s diameter. They were originally found and identified in Australia, but many scientists think the amoeba actually evolved elsewhere—most likely in the United States. They can be found all across the globe, anywhere there’s warm freshwater: lakes, ponds, rain puddles, aquariums, rivers, streams, and natural springs. Alarmingly, Naegleria fowleri has also been found in hot tubs, swimming pools, wells, and city water systems.

Scroll to Continue

Read More From Youmemindbody

Tick-borne virus is one of the causes of meningoencephalitis.

Tick-borne virus is one of the causes of meningoencephalitis.


Meningoencephalitis is an inflammation of the brain and the meninges. The meninges are the protective membranes that cover the brain and the spinal cord. You’ve heard of meningitis, an inflammation of the meninges. You’ve also heard of encephalitis, an inflammation of the brain. Think of meningoencephalitis as sort of a combination of these two other medical conditions.

Meningoencephalitis causes are numerous and varied. It can be caused by bacteria, including Rickettsia prowazekii, Listeria monocytogenes, and Neisseria meningitidis. These bacteria can be spread by lice, contaminated foods, and through body fluids of infected individuals, respectively.

Other causes of meningoencephalitis are viruses: mumps, HIV, herpes simplex I, and West Nile. Ticks can also carry a virus that causes the disease. Spores from the fungus Cryptococcus neoformans can also cause meningoencephalitis. Protozoa that can cause the condition include Toxoplasma gondii and Trypanosoma brucei, along with several protozoa that cause primary amoebic meningoencephalitis, or PAM, including Naegleria fowleri.

Not everyone who is exposed to Naegleria fowleri develops meningoencephalitis or PAM. It appears that many individuals have a natural resistance, and PAM cannot be spread from person to person. For some reason, most victims are male, and over half are children. Doctors and scientists aren’t even sure how many people are affected by PAM each year. Because the symptoms are very similar to those presented with meningitis, some patients are diagnosed with meningitis when, in fact, they have primary amoebic meningoencephalitis.

Meningoencephalitis Symptoms

As I’ve already mentioned, the symptoms of meningoencephalitis are similar to the symptoms of meningitis. These include pain or stiffness in the neck, headache, nausea, vomiting, and fever. I had meningitis as a child, and these were the exact symptoms I experienced. I can still remember how badly my neck and head hurt. Other meningoencephalitis symptoms might include a sore throat, a drooping eyelid, changes in taste or smell, diarrhea, confusion, hallucinations, coma, or seizures.

Meningoencephalitis symptoms can show up as quickly as two days after the amoeba has entered the body, or it might take as long as two weeks for symptoms of meningoencephalitis to manifest. The usual incubation period is three to six days. PAM is a deadly disease that only three known confirmed victims in the United States have survived. Scientists have found drugs that eliminate Naegleria fowleri in laboratory conditions, but they don’t seem to work in actual humans. That’s why prevention is so important.

Naegleria fowleri can't survive in saltwater, thank goodness!

Naegleria fowleri can't survive in saltwater, thank goodness!

Travel Tips

If you’re planning a trip to an area where Naegleria fowleri is present, use some travel tips that will help ensure the safety of you and your family. Of course, it’s best to completely avoid swimming, diving, or snorkeling in any freshwater body, but since most Americans love water sports, that’s not likely to happen. When you do get in any type of untreated warm freshwater, keep your head above water at all times, or at least use a clip that keeps your nostrils shut tightly, or plug your nostrils with nose plugs. Because many scientists believe that higher concentrations of Naegleria fowleri are found in the mud at the bottom of the water, it’s best not to disturb it. Also, when you’re using a neti pot with water that you’re not sure is safe, boil the water first for four or five minutes. Naegleria fowleri can survive at temperatures to only around 113-114 degrees, so bringing the water to the boiling point should kill any amoeba. Also, think twice before swimming in strange swimming pools and getting in strange hot tubs, and if you have your own, make sure the water is treated with the proper chemicals.

Fortunately, you don’t have to worry about these travel tips if you’re swimming in the ocean or some other body of saltwater. Naegleria fowleri can’t survive in saltwater. I found this fact very comforting, as most of our vacations take place near the Atlantic Ocean or the Gulf of Mexico, and all my family members enjoy swimming, boogie boarding, and snorkeling. If, on the other hand, you’re considering enjoying a dip in warm freshwater, use safety precautions to avoid any possible Naegleria fowleri amoeba and a resulting case of meningoencephalitis.


Gholipour, Bahar. "Brain-Eating Amoeba: How One Girl Survived." August 14, 2013. LiveScience.

Jacobson, Roni. "What Happens When an Amoeba Eats Your Brain?" July 18, 2014. Scientific America.

"Primary Amoebic Meningoencephalitis." February 28,2017. CDC.

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.


Muqaddam on July 31, 2015:


Liz Elias from Oakley, CA on July 26, 2015:

Congrats on HOTD, Habee!

This, indeed, would make for a stunning horror flick! How scary! You've done a bang-up job of researching and presenting your findings.

I had never heard of such a thing, either, and I've been a freshwater swimmer and water-play person all my life. I'm not a big fan of salt water.

For one thing, growing up in San Francisco, 'beach weather' is nearly non-existent, and the Pacific is much colder than the Atlantic, anyway. No matter the weather, you shouldn't be in the water much deeper than your thighs without a wetsuit. That's not to mention our ferocious rip currents. The surfers risk it all, but the Pacific is not really a swimmer's ocean. ;-) So I grew up swimming in the indoor municipal pools. I doubt much survived in those--you'd come out with your eyes burning from the chlorine!

(And btw--I, too, learned the spelling as "amoeba," and I spell it that way still! So there! LOL)

Voted up, interesting, useful, shared and pinned.

Peggy Woods from Houston, Texas on July 26, 2015:

That is certainly scary information about the deadly amoeba. Yes, I learned to spell it with the "o" in it years ago. Good thing that salt water is safe. Now, if only those sharks in the water would stay out from the shorelines, everything would be perfect! Lots of shark action this year has been reported. Hope you have a great and safe vacation. Will share this so that others can learn of this and those who have swimming pools need to keep those chemicals in balance.

Marlene Bertrand from USA on July 26, 2015:

As I was reading this, I kept thinking about how I would probably never go in the ocean again. So, discovering that this organism does not do well in salt water is comforting. By the way, congratulations on receiving the Hub of the Day award.

Kristen Howe from Northeast Ohio on July 26, 2015:

Holly, congrats on HOTD! This is an interesting hub about ameba bacteria. Very compelling to know how it can kill people too by eating their flesh. Voted up!

Kylyssa Shay from Overlooking a meadow near Grand Rapids, Michigan, USA on July 26, 2015:

I have to second Ben Zoltak's drawn-out damns. I'd actually heard of this particular amoeba before, but I was unaware it lived as far North as it does or in flowing water as well as in stagnant water. I also didn't know it takes such hot water to kill it. That bit of information is vital for folks who think they can keep their hot tubs hot enough to dispense with chemical treatments.

Thank you for sharing this information. It could very well save lives.

Randy Godwin from Southern Georgia on July 26, 2015:

I had a brain eating virus one time. Fortunately, it starved to death.:P

Mary Hyatt from Florida on July 26, 2015:

Congrats on HOTD! I've lived in S. Florida for many years, and we have lots of fresh water ponds, etc. I've never allowed my children to swim in them for fear of alligators.

Very interesting and informative Hub! Voted UP, etc.

Ben Zoltak from Lake Mills, Jefferson County, Wisconsin USA on July 26, 2015:

Daaaaaaaaammmmmnnnnnnnn! So that's why people where nose plugs. I snorkel all the time...daaaaammmmmmmmmnnnn! This stuff sounds nasty, here I was just thinking how it might be interesting to brush up a bunch of the sand at the bottom of our lake to look for treasure, guess I'll just stick to surface treasure, less amoebae!

Cheers to never getting any kinda Meningits!


Holle Abee (author) from Georgia on July 01, 2013:

Mike, you're very welcome! Thanks for visiting.

Holle Abee (author) from Georgia on July 01, 2013:

Kyle's mom, I'm so sorry for your tragic loss. I'll check out your site. I'm glad people are becoming more aware of this deadly ameba!

Mike Robbers from London on July 01, 2013:

Interesting and informative hub. Wasn't aware of the ameba parasite so thanks for providing so many useful info.

Kyle's mom on June 30, 2013:

thank you habee for helping spread the amoeba awareness and we hope your grand kids and many others will be protected from the brain eating amoeba. Our family started a foundation for awareness after our son Kyle passed away from PAM caused by this horrible amoeba. You can read Kyle's story and other's at as well as view our pages of awareness....and we have nose plugs!! take care and thank you! Swim Safe and Spread the Awareness

Holle Abee (author) from Georgia on June 30, 2013:

Right, Doc. I'm a lot more afraid of brain eating amoeba than I am of zombies! lol. I'm sure we have Naegleria fowleri here in South GA, and my grandkids often swim in freshwater here. Guess I need to buy some nose plugs/clips!

drbj and sherry from south Florida on June 30, 2013:

I, too, learned to spell the word as amoeba, Holle, and when I see it spelled ameba it looks very wrong. What a dastardly substance it is. Now I know that zombies aren't the only brain-eaters to be feared. Thanks for this important lesson - stay out of freshwater lakes, rivers, streams, ponds, etc.

Holle Abee (author) from Georgia on June 30, 2013:

Wow, John - I really appreciate your comment! Anything having to do with the brain/CNS is serious, including meningitis. I had it when I was 6 years old, and it took me a long time to completely recover. Good idea about the nose plugs. I'll add that to the hub.

John R Wilsdon from Superior, Arizona on June 29, 2013:

SO MANY INTERESTING FACTS! Where to begin? I have found many doctors may have been sleeping in medical school. My dad's urologist thought BCG was an acid! So much for that expectation.

With regard to your recommendation, I would keep my kids out of that natural water. Rather than a nose clip, wouldn't it be better to stuff something non-permeable up the nose?

No form of meningitis is anything to mess with. My sister-in-law nearly died when pregnant from meningitis. Inflammation of the brain is always dangerous.

The amebas, amoebae thing is that darned Latin. ae suffix is the feminine plural, and of course our plural, which makes more sense (lol), involves just adding an s.

This information was all new. I will be forwarding it to all I know, including Twitter. Thanks for possible a life- saving hub.

Related Articles