A person is hospitalized in St. Louis after contracting a rare infection from a deadly waterborne amoeba, the Missouri Department of Health and Senior Services reported Wednesday.
State health officials can't say for sure where the patient contracted the amoeba but said the person had been waterskiing at the Lake of the Ozarks in the days before becoming sick.
The amoeba, Naegleria fowerli, is a single-celled organism that lives in hot springs, lakes and other warm freshwater bodies and often proliferates during the hot summer months.
In the rare cases in which a person contracts the amoeba, it enters through the nasal cavity and works its way to the brain, where it causes deadly swelling called primary amoebic meningoencephalitis. Some people refer to it as a "brain-eating" amoeba.
"The brain cells die, and they die very rapidly, so that's probably how it got this name," said Dr. Christian Rojas Moreno, an infectious diseases physician at University of Missouri Health Care. "The inflammation is severe – so severe that the brain cells die from this infection."
Although the Centers for Disease Control and Prevention reports fewer than 170 people have contracted the amoeba since 1962, the infection is almost always fatal, with 97% of patients dying of it.
Doctors can treat the infection with intravenous antimicrobials, Rojas Moreno said.
DHSS spokeswoman Lisa Cox said she couldn't give any more updates on the waterskiing patient, but said they were only the third person in Missouri to contract the amoeba since the state began keeping records. (Other Missourians were infected in 1987 and 2022.)
"If there's any positive side to this at all, it's something we have a very good grasp on how often it is happening, because it is so severe," Cox said. "It's not something that we're missing."
It's unlikely the state would outlaw swimming or other water recreation over the case, because the amoeba is so widespread in fresh water, she added.
"You'd be likely to find a positive result anywhere," Cox said. "[But] what we can do is share information about how to prevent it if people are concerned about the risk."
The Missouri Department of Natural Resources does not have the ability to test for Naegleria fowlleri, said Brian Quinn, an information officer with the state agency, and doesn't know of any Missouri labs that routinely test for the organism.
"CDC and the Department of Health and Senior Services do not recommend testing for the amoeba in natural, untreated water bodies," Quinn wrote in an email. "Further, even detectable concentrations have little relationship to the risk of infection and infections are extremely rare. Therefore, we concur with public health experts that closing any natural water body would not be recommended."
People can't contract Naegleria fowleri from swallowing water, only from it going into the nose. It's not spread through person-to-person contact.
To stay safe, people should hold their nose shut, use nose clips or keep their head above water when swimming or floating in warm freshwater bodies, especially when swimming, jumping or diving.
Swimmers should also avoid putting their head under the water in hot thermal springs and avoid digging in or kicking up sediment on the bottom of lakes, ponds and rivers, where the amoeba lives.
Experts emphasized that although the amoeba is common, contracting it is exceedingly rare.
"The amoeba is present pretty much everywhere, especially in warm fresh water, especially during summertime and high temperatures," Rojas Moreno said. "There is a risk…[but] there have been a handful of cases in many years, and there are billions of exposures."
This story has been updated with comments from Christian Rojas Moreno and the Missouri Department of Natural Resources.
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