'Brain-eating' infections could become more common, scientists warn

2023 was the hottest summer in the past 2,000 years, and summer 2024 is looking to be just as intense. As summer peaks, freshwater lakes and pools all over the United States will likely be filled with people trying to cool off. But as the temperatures of these freshwater environments rise, the organisms that live in them can shift, posing harmful, or even lethal, threats to swimmers. 

Naegleria fowleri is one such threat that seems primed to start infecting more people — but surprisingly, it hasn't done so yet. 

N. fowleri is a single-celled organism that loves warm temperatures, lives in soil and fresh water, and preys on bacteria, much like many others of its kind. The amoeba can lurk in lakes, rivers, hot springs, well water, tap water and poorly maintained swimming pools, among other water sources. 

What's harrowing about this tiny organism is that it can enter the brain via nerves in the nose and then decimate brain cells. This rare infection can lead to a fatal condition called primary amoebic meningoencephalitis (PAM), which is why N. fowleri is commonly known as a "brain eating amoeba."

Related: Rare 'brain-eating' amoeba infection behind death of 2-year-old in Nevada 

N. fowleri infections that lead to PAM are relatively rare in the U.S., averaging about zero to eight laboratory-confirmed cases per year. Although all incidents of PAM are caused by an N. fowleri infection, this fatal disorder can sometimes be misdiagnosed as other, more-common infections of the nervous system, such as bacterial meningitis and viral encephalitis. Such misdiagnoses may mean that some cases of PAM are missed.

Symptoms of PAM typically start one to 12 days after a person is exposed to the amoeba, and patients die within one to 18 days of symptoms starting. Testing for an N. fowleri infection is also a slow process, further complicating diagnosis, and there are no specific drugs to kill the amoeba.