A new study has revealed high concentrations of Naegleria fowleri in bodies of water at three sites managed by the National Parks Service (NPS), Yellowstone National Park, Grand Teton National Park, and Lake Mead National Recreation Area. Naegleria fowleri is best known as the “brain-eating amoeba” found in bodies of warm freshwater, which causes a fatal brain infection called primary amoebic meningoencephalitis (PAM). According to the CDC, death can occur within 1 to 18 days of typical meningitis symptoms, including headache, fever, and stiff neck, and the overall fatality rate exceeds 97 percent.
The study was published in ACS ES&T Water after researchers analyzed water samples from 40 bodies of water across five different sites managed by the NPS: Yellowstone National Park, Grand Teton National Park, Newberry National Volcanic Monument, Olympic National Park, and Lake Mead National Recreational Area. A total of 185 water samples were collected between 2016 and 2024, returning high concentrations of Naegleria fowleri in 63 of them (34 percent).
At Yellowstone, Naegleria fowleri was present in the Firehole River, Boiling River, and Lewis Lake hot springs. It was found in Polecat, Huckleberry, Granite Hot Springs, and several other recreational bodies of water throughout Grand Teton National Park. And several more bodies of water at Lake Mead Recreational Area returned high concentrations, such as Boy Scout, Rogers Hot Springs, and more.
Fewer than 10 cases of PAM are reported in the U.S. each year, with a total of just 167 recorded between 1962 and 2024. In 2018, 29-year old Fabrizio Stabile traveled to then-BSR Cable Park in Waco, Texas, where he surfed in the wave pool and contracted PAM, dying days later when he returned home to New Jersey. A CDC investigation of the conditions at the park’s “surf lagoon” confirmed the presence of Naegleria fowleri even though a press release from the park contradicted those findings, and a wrongful death lawsuit against the park’s ownership ensued. The park has been under new ownership since 2021 and rebranded to Waco Surf.
