Deadly Amoeba Lurks in Popular US Park Waters

A recent multi-institutional study has identified the brain-eating amoeba, Naegleria fowleri, in water samples from popular recreation areas within U.S. national parks. Conducted between 2016 and 2024, the research sampled 40 locations, finding the amoeba in 34% of them.

Yellowstone National Park and Grand Teton National Park in Wyoming, along with Lake Mead National Recreation Area in Nevada, had positive test results. The amoeba, which is commonly found in warm freshwater globally, can cause a nearly fatal brain infection known as primary amebic meningoencephalitis (PAM) if water enters the nasal passages. Infection rates are low, with fewer than 10 deaths annually in the U.S., but the fatality rate for PAM is extremely high, with only four survivors out of 167 reported cases between 1962 and 2024.

Researchers observed that Naegleria fowleri has been migrating northward since 1962, a trend expected to continue with rising global temperatures. They are urging for enhanced monitoring systems, improved risk management, and public awareness campaigns to address this evolving threat.