Brain-eating amoeba remains rare, and deadly

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By Maggie Fox

A 12-year-old Arkansas girl infected with a brain-eating amoeba is on the mend and may be only the third person known to have survived the baffling infection, doctors said Wednesday. She’s recovering just as a 12-year-old boy in Miami struggles for his life with the same infection.

Doctors note the infection is still extremely rare – so rare that health officials don’t know how to track it or protect against it. They’re also not sure why Kali Hardig of Little Rock appears to be recovering, but federal health officials are relaying details about her treatment to the team treating Zachary Reyna in Miami.

The amoeba is called Naegleria fowleri, and it’s found in warm, fresh waters all over the world. It’s been seen in hot springs and swimming holes, freshwater lakes and even in neti pots used to clean out sinuses. 

It infects people through the nose, traveling up the nerve cells that carry smell signals into the brain. Doctors are not sure how or why a very few people are susceptible, but it’s clear that having water forced up into the sinuses, perhaps by dunking or diving, is an important factor.

Kali became ill after swimming at a water park fed by spring water in Little Rock. Doctors at Arkansas Children’s Hospital tried the standard approach – a cocktail of four antibiotics – but also used an experimental antifungal drug and an unusual approach that involved lowering her body temperature.

“Whether that had an impact on her care is hard to say,” Dr. Matt Linam, an infectious disease specialist at Arkansas Children’s, told NBC News. But after three weeks in the hospital, Kali is semi-conscious.

“She hears when they ask a question and can shake her head yes or no and give a thumbs up,” hospital spokesman Tom Bonner said.

The infection caused by N. fowleri is called primary amoebic meningoencephalitis – PAM for short. It’s an inflammation of the brain and because an amoeba causes it, there’s not an easy treatment. The early symptoms look a lot like a cold or flu, so it can take a while to diagnose. Meanwhile, the amoeba is feeding on brain cells.

Symptoms don’t usually begin until about a week after someone’s been in the water, so it is not always immediately clear what the cause might be. “PAM is difficult to detect because the disease progresses rapidly so that diagnosis is usually made after death,” the CDC says.

Kali was lucky because she got treated fast, Linam says. Her mother knew something was badly wrong and got her to the hospital.

“Our lab was able to identify the Naegleri pretty quickly,” Linam says. “That gave us a leg up. We were able to get started on the right medicines early. Even six to 12 hours later and we probably wouldn’t be having this conversation.”

Only about 130 cases of Naegleri infection have been reported since 1962, making it one of the rarest of infections. For that reason, it’s almost never the first thing doctors would suspect.

“With thousands and thousands, if not millions, of people swimming in warm, fresh water in the south, just having the story that someone went and swam in a lake or something like doesn’t mean you are going to get Naegleria,” Linam says.

“Hundreds of millions of visits to swimming venues occur each year in the U.S. that result in 0-8 infections per year,” the CDC says on its website. “The extremely low occurrence of PAM makes epidemiologic study difficult; it is unknown why certain persons become infected with the amoebae while millions of others exposed to warm recreational fresh waters do not.”

And Kali did not look any different at first – although doctors were very worried because bacterial meningitis is extremely dangerous.

“She presented with symptoms consistent with meningitis. She looked sick enough that our ER physicians felt she needed a spinal tap,” Linam said. “They were thinking bacterial meningitis. There was nothing about her story at that point that sent us down path worrying about Naegleria.”

But then lab technicians spotted the amoeba. “It put us on the right track,” says Linam.

Her doctors sedated her, put her on a breathing machine, lowered her temperature, administered the cocktail of antibiotics that’s been used to treat the infections before, and asked permission to try miltefosine, an experimental drug that appears to work against parasites.

The CDC has a small supply for use against cases like Kali’s. “We went through the Food and Drug Administration hoops to get approved to use it,” Linam says. He’s not sure whether it helped, but says magnetic resonance imaging (MRI) brain scans show Kali is improving.

“Once things settle out a little more our hope is actually to sit down and take all the information that we learned from Kali’s case and get it down on paper in the hopes we can give other doctors something to jump off from,” Linam says.

Zac’s case started out in a similar way to Kali’s. “We thought he just got a virus,” Zach’s brother, Brandon Villareal, told NBC affiliate WBBH. “He slept all day, all night.” 

Zac is still in intensive care at Miami Children’s. According to a Facebook page his family has set up, “Zac is still fighting. Doctors are saying things have not changed.”

People often demand that public health officials test water for the amoeba. “However, no method currently exists that accurately and reproducibly measures the numbers of amoebae in the water,” the CDC says. “This makes it unclear how a standard might be set to protect human health and how public health officials would measure and enforce such a standard.”