A rare amoeba with a fatality rate of 97 percent has infected a man living in Florida. The amoeba, which is found in freshwater from lakes, rivers and hot springs, enters the body through the nose and causes catastrophic brain damage. Florida State’s Department of Health (DoH) has issued a warning to residents but advises that wild swimming can still go ahead this summer so long as effective precautionary measures are put in place.
Humans contract Naegleria fowleri by inhaling contaminated water carrying the amoeba, which travels to the brain via the olfactory nerve. Once in the brain, N. fowleri rapidly multiplies, gorging on brain tissue. This triggers an immune response from the body causing the brain to swell, fatally damaging the organ.
Infected patients experience a range of symptoms including headache, fever, nausea and vomiting, disorientation, seizures, and hallucinations. Unfortunately, the presentation is almost a mirror image for meningitis, which means treatment is often delayed due to misdiagnosis. While a rare disease globally, most infections occur in the southern states of the US with an annual peak in the summer months when more people are out swimming.
The state’s DoH has warned locals to avoid nasal contact with freshwater, including taps and not to do anything to stir up sediments that could churn up populations of this free-living amoeba. N. fowleri doesn’t need a host to survive and is perfectly harmless if swallowed, but when water shoots up the nose, as often happens when diving, it spells disaster. However, the DoH said, "Remember, this disease is rare and effective prevention strategies can allow for a safe and relaxing summer swim season."
Of the 145 known cases of N. fowleri in the US, only four have survived. The devastating infection is a rare one, but experts fear the amoeba’s preference for warm, fresh water combined with increasing water temperatures due to climate change has seen a gradual increase in cases in northern US states.
"Through the first several decades that we tracked it, we really only knew of cases in the southern tier of the US," said Centers for Disease Control and Prevention (CDC) epidemiologist Jonathan Yoder in an interview with Insider. "But in the last 10 years, we have identified cases in additional northern states, like Indiana, Minnesota, Missouri, where we had not previously seen cases."
The concern goes beyond the US, as experts warn it's possible that increasing water temperatures across the planet could see this amoeba thriving in environments that were once unsuitable. In a statement to Insider, associate professor Travis Heggie from the Bowling Green University, who once oversaw public safety programs for the US National Park Service, warned, “This amoeba is found in soil profiles around the world, and it's naturally occurring."
What causes the disparity between the amoeba’s prevalence in nature and the comparatively low number of infections is not yet known, but for Americans, the CDC advises that recreational water users should assume that N. fowleri is present in warm freshwater and take appropriate precautionary steps accordingly.