Climate change may have sparked a disturbing migration. A new study says infections tied to Naegleria fowleri—or "brain-eating amoeba"—are occurring farther north than they once did, LiveScience reports. The single-celled organism is typically found in warm bodies of freshwater, per Newsweek, making it historically more common in southern states. But now more cases are occurring in the Midwest. Such cases arise when N. fowleri is ingested through the nostrils, allowing it to enter a person's brain, which causes a rare and often fatal infection called primary amebic meningoencephalitis (PAM). The findings—which note that the annual case count remains steady—are based on 85 cases of PAM over 40 years.
Of those cases, 74 occurred in the South; six occurred in the Midwest, including Minnesota, Kansas, and Indiana, with five of those after 2010. The study calculated a 8.2-mile-per-year northward trend in cases. "It is possible that rising temperatures and consequent increases in recreational water use, such as swimming and water sports, could contribute to the changing epidemiology of PAM," the study’s authors write. PAM symptoms include headache, nausea, and vomiting, before moving to stiff neck, seizures, and coma. On average, it causes death in about five days. It has been linked to two recent deaths, per Newsweek, including a 13-year-old in Florida and a 6-year-old in Texas. (In September, officials in Texas warned residents not to use tap water due to N. fowleri.)