North Carolina teen's rare brain infection highlights northward spread of heat-loving amoeba
A teenager in central North Carolina is in critical condition with a Naegleria fowleri infection as researchers note a gradual northward shift in the organism’s range linked to rising temperatures.
A central North Carolina teenager is in critical condition after contracting a brain infection caused by the amoeba Naegleria fowleri, a disease traditionally associated with the hottest summer days in the Southern United States. State health officials have not disclosed where the teen was exposed to the organism.
Scientists say the overall number of U.S. cases has remained low, but the locations of exposure have moved northward over recent decades. A 2021 CDC-led study of 85 recreational-water cases from 1978 to 2018 found the northernmost exposure site shifted about 13.3 kilometers (8.3 miles) north each year, although annual case counts ranged from zero to six with no statistically significant upward trend.
The study identified a temperature signal: in the two weeks before exposure, daily high and low temperatures near the sites were on average 0.8 °C (1.4 °F) above the 20-year norm for that location and time of year. While the analysis could not prove causation, it aligns with the organism’s preference for warm water up to 45 °C (113 °F). When water cools, the amoeba can persist in a dormant cyst form and reactivate as temperatures rise.
Since 2010, infections have been confirmed in states such as Nebraska, Iowa, Minnesota, Indiana, Maryland and northern California, expanding beyond the traditional Southern pattern. Researchers warn that warmer water earlier in spring or later in fall could lengthen the period of suitable conditions, potentially increasing the window for exposure.
"It’s heat-loving. It’s a single-celled organism," said Dr. Tyler Evans, an infectious disease physician and public health expert.
"We might see not necessarily just an increased risk of cases per se, but the times in which the cases are presenting," Evans added.
The disease, primary amebic meningoencephalitis (PAM), occurs when contaminated water enters the nose and the amoeba travels to the brain; it cannot be contracted by swallowing water or through person-to-person contact. The CDC has recorded 180 diagnosed U.S. cases from 1937 through 2025, with annual counts ranging from zero to eight, and the condition is almost always fatal.
Public health guidance advises swimmers to treat warm freshwater as potentially hazardous, using nose clips, keeping the head above water and avoiding disturbed sediment in shallow areas. Officials emphasize the need for continued surveillance and preparedness as heat-adapted pathogens may encounter new geographic and seasonal opportunities.