In late July 2013, a 5-year-old boy played outside on a slip 'n' slide in St. Bernard Parish, Louisiana, like it was any other nice day that summer. But a week later, he came down with a high fever and splitting headache. It only got worse from there, and he died on Aug. 1 of severe brain swelling. The postmortem diagnosis: a nearly always fatal infection called primary amebic meningoencephalitis, which is caused by Naegleria fowleri, also known as the brain-eating amoeba.
Tests showed that the protozoan was present in the water at the house where the boy was staying, and that he was likely exposed while playing on the slip 'n' slide, making it the first recorded infection from treated tap water in the United States. Doctors didn't immediately suspect N. fowleri because the initial symptoms are identical to bacterial and viral meningitis. And the amoeba was thought to live primarily, and infect people, in lakes with warm water.
About a day before the boy became infected, and one state to the north, 12-year-old Kali Hardig was driven to a Little Rock hospital with very similar symptoms: a fever of 103 degrees Fahrenheit, pain in the head and drowsiness. A week earlier, her parents said, she went swimming in several bodies of water, including a muddy pond. Given this fact, and the elevation of white blood cells in the girl's spinal fluid, the doctors suspected it could be this rare disease. So they performed a staining technique that revealed the presence of amoebae. A further DNA test confirmed it was indeed N. fowleri, according to a study describing the case published online this month in the journal Pediatrics.
Doctors at Arkansas Children's Hospital put the girl on a cocktail of antibiotics. They also phoned the CDC, requesting an experimental drug called miltefosine that had been shown to have some activity against amoebae, and this experimental pharmaceutical arrived a day and a half later.
But realistically, the odds were stacked heavily against Kali, just as they were against the boy in Louisiana. At that time, only two people were known to have survived the infection in North America.
Kali would become the third.
As explained in the study, authored by scientists and physicians including Dr. Matt Linam, who treated Kali, the main key to her survival was quick detection. She was put on antibiotics within about six hours of admission, and the miltefosine 24 hours after that.
The team also induced hypothermia by putting chilled pads on the outside of her body, lowering it to 90 degrees Fahrenheit. This is sometimes done with patients who have traumatic brain injuries. The procedure may help reduce swelling and herniation in the brain, which is ultimately what kills people with this infection, says Jennifer Cope, a study co-author and medical epidemiologist for the CDC in Atlanta.
"She survived from a combination of early recognition and diagnosis, and aggressive treatment," Cope says.
But it's nothing short of miraculous that she made a complete recovery, Cope adds. Six months after being released from the hospital, Kali didn't appear to have any lasting deficits, according to the study. She was perfectly healthy.
The scientists hope that the steps they take will help doctors treat other people with this infection in the future, but the disease remains a typically fatal one. It is possible that Kali was infected with a less virulent form of the amoeba, or had some immunity against it, though neither of these factors is certain, Cope says.
"There's not a lot known about this organism," says Francine Marciano-Cabral, a microbiologist at Virginia Commonwealth University who studies N. fowleri. Studies she's been involved with have shown, for example, that most people tested in southern states have antibodies against the amoeba. This suggests that many people can be exposed, perhaps through ingesting the amoeba, and may develop some resistance to it.
Still, only up to eight people get infected each year; in total there were 162 cases of N. fowleri reported to the CDC between 1962 and 2013. To put that in perspective, about 130 people become infected with HIV in the United States every day, on average.
Infections usually occur when people go swimming in warm waters where the amoeba lives, throughout the South, and get water up their noses. From there, the amoeba makes it to the brain through the olfactory canal, the link between the nose and the brain. Though the range of the protozoan is expanding—in the last couple years, cases have been reported in Minnesota, Kansas and Indiana—infections don't appear to be getting more common.
As for what people can do to avoid it: wear nose plugs when swimming in warm outdoor water, especially muddy water (the amoeba is often found in wet soil and lake-bottom sediment). And sterilize water before doing a nasal rinse or using a neti pot—several people have become infected and died from primary amebic meningoencephalitis after using unsterilized water.
"Really the only way to completely eliminate risk of infection is to not put your head underwater," Cope says.
