Heading West This Summer, Iowa? What to Know About the Brain-Eating Amoeba Found at Several National Parks

Like a lot of Iowans, my family has been planning our summer trip out west. The plan is to spend some time hiking around Medicine Bow Peak in Wyoming, take in the views, several trails and lakes, and then relax in the hot springs near Saratoga afterward. Honestly, it sounds about perfect to me.

Then I came across a newly published scientific study about the so-called “brain-eating amoeba” being detected in several popular hot springs and thermal recreation areas across the western United States. Things that give you the creeps, am I right? Well, it certainly got my attention. The organism is called Naegleria fowleri. Scientists recently confirmed its presence in places like Yellowstone National Park, Grand Teton National Park, and Lake Mead National Recreation Area.

Anything called a “brain-eating amoeba” is going to make people stop scrolling. But after digging into the actual study, the situation is a little more nuanced than the scary headlines make it seem. And, come on, there is always some risk in life; that's part of what makes it interesting.

By Centers for Disease Control and Prevention - https://www.cdc.gov/parasites/naegleria/pathogen.html, Public Domain, Link

In the case of Naegleria fowleri, the infection caused is extremely rare. Millions of people visit these parks, rivers, and hot springs every year without getting sick. At the same time, the infection is incredibly serious when it does happen. That's why researchers are paying close attention to where the organism is showing up. Just how serious is an infection? It has a fatality rate above 97%. If you get it, it will most likely kill you and will most certainly leave you with devastating disabilities should you survive.

Despite it's name, Naegleria fowleri is not some invisible monster hunting humans in every body of water. It is a microscopic, single-celled amoeba that naturally lives in warm freshwater, geothermal pools, hot springs, and slow-moving river sections. The CDC states this on their page: "You should assume that Naegleria fowleri is present in all lakes, ponds, rivers, hot springs, and other fresh water." How comforting.

The real danger comes when contaminated water enters the nose. From there, the amoeba can travel to the brain and cause the rare infection called primary amebic meningoencephalitis, or PAM. Early symptoms feel similar to the flu. People develop headaches, fever, nausea, or vomiting. As infection increases, symptoms become severe and include confusion, seizures, and coma. And as mentioned before, the fatality rate is extremely high. That's why this organism gets so much attention when a new case occurs, or new research is published.

The study from the American Chemical Society, looked at 185 water samples collected between 2016 and 2024 across several western recreation areas. Researchers detected the amoeba in Yellowstone National Park, Grand Teton National Park, and Lake Mead National Recreation Area.

Several Wyoming hot springs tested positive during the study, including Polecat Hot Springs, Huckleberry Hot Springs, and Granite Hot Springs. That really stood out to me because Saratoga hot springs and the Medicine Bow area are exactly the kinds of places many Midwestern hikers look to, just like my family is planning. I mean, after a long hike, sitting in a hot spring sounds pretty good to me.

Now, if you want to avoid this little bugger all together, stick with cold water! One thing researchers made very clear is that this amoeba prefers warm water. The study found it surviving in waters ranging from roughly 64 degrees to nearly 131 degrees Fahrenheit. That is why scientists are focused mostly on geothermal pools, thermal runoff, and warmer recreational waters.

Even after reading through the study, I am still planning to visit Wyoming. I am just going to be smarter about the water. Not that it's a pleasant experience to get water up your nose in the first place, but maybe going back to nose plugs when swimming in ponds, rivers, and lakes isn't such a bad idea. I'm a dad, I can handle looking goofy; however, I'll likely not survive brain-eating amoeba. When it comes to the kids, I may need to be a bit smarter though.

Health experts say the biggest thing people can do is avoid getting warm freshwater up their nose. Activities like diving, rough underwater play, cliff jumping, wakeboarding, tubing, and aggressive splashing carry the greatest risk because they can force water deep into the nasal passages. Think sinus infection, but on a whole other level. Here's some food for thought, the demographic with the most cases of PAM were males aged 10 to 14. In fact, males (134) accounted for about three times as many cases as females (45).

The horsing around part is the big thing to take into consideration here. Researchers say to avoid stirring up bottom sediment in warm water areas because the amoeba call the mud and sediment near the bottom their home. Additionally, researchers say the amoeba can transform into a dormant cyst during unfavorable conditions, then become active again when temperatures improve. Scientists believe that may help explain why cases and detections have gradually expanded farther north and west over time.

Historically, most infections happened in more southern states. More recent cases, however, have appeared in places like Nebraska, Iowa, and Minnesota. Researchers believe warming water temperatures may gradually expand the areas where the amoeba can survive.

To be clear, the study’s authors were not trying to scare people away from national parks, hot springs, or western vacations. Their message was mostly about awareness and smart risk reduction. Millions of people safely visit Yellowstone, Grand Teton, and various springs (hot or cold) across the U.S every year and the cases are still extremely rare.

After reading the study myself, my takeaway is pretty simple. I'm still taking the trip. I'm still summiting Medicine Bow Peak. And I'll still check out the hot springs near Saratoga. I'm just going to think a little more carefully before dunking my head underwater.