Q. If the "brain-eating parasite" that has made the Benton child so sick is common, why don't more people have it? Should I be careful swimming in Arkansas's lakes and streams? Why did she survive when so few do?
A. Kali Hardig, the 12-year-old girl being treated at Arkansas Children's Hospital for primary amoebic meningoencephalitis (PAM), caused by the parasite Naegleria fowleri, is "very blessed," ACH intensivist Dr. Mark Heulitt said last week.
Kali, who was admitted to Children's July 19 with a high fever and vomiting, apparently contracted the amoeba while swimming at Willow Springs Water Park in south Little Rock. Only two people in North America have survived infection by the amoeba; Kali will be the third. (A child in California and another in Mexico also survived.) She is no longer in critical condition; she left the intensive care unit late last week to begin rehabilitation. She is able to follow commands and make thumbs up or down responses, which is a good indicator of higher brain function, Heulitt said, but she is not yet talking.
While the amoeba is not rare — it lives in the mud under warm lakes and slow rivers — infection is: Only 128 cases of PAM have been reported in the United States since 1962. Because the disease kills quickly — as soon as within a week — it may go undetected. Doctors don't know why some people are vulnerable and some aren't.
The amoeba moves through the porous plate behind the sinuses to reach the brain, where it damages tissue. "The risky behavior is not just getting wet but forcibly pushing water up the nose," state Health Department epidemiologist Dr. Dirk T. Haselow said, the way it might be if you fall face forward off water skis or kick up mud from the bottom of a pond. It can also live in water pipes; two Louisiana women who used tap water to perform a nasal wash with a neti pot became infected and died.
Heulitt got a call from a Miami hospital last Thursday after another child was admitted there with PAM. The federal Centers for Disease Control had recommended that the hospital contact Kali's doctors to discuss their protocol.
Kali was first treated with antibiotics and antifungals and a catheter was placed in her brain to reduce swelling. Her condition worsened and she had to be intubated, Heulitt said. At that point, ACH critical care Dr. Jerril W. Green lowered her body temperature to 34 degrees C. (93.2 F.) to further reduce swelling, and, with the OK of the CDC, doctors gave Kali the anti-parasite drug miltefosine, a German drug not approved for use in the U.S. by the Federal Drug Administration. Miltefosine was developed to treat breast cancer but has been found to be effective against the water-borne parasite that causes leishmaniasis.
Why Kali has survived is unknown. "With a single case, it's hard to draw much of a conclusion," Heulitt said. "We don't know if she had as much exposure as other people."
Heulitt did not credit the German drug for Kali's recovery altogether; he said her mother's speedy action in getting her to the hospital was a factor. A 7-year-old boy admitted to Children's with PAM in 2010 — he'd also been swimming at Willow Springs — was also treated with miltefosine, the Health Department's Haselow said, but he died. The owners of Willow Springs have closed the park.
Naegleria also occurs in hot springs. A spokesman for the Centers for Disease Control said it has done no testing for the bacteria in Arkansas other than the one that confirmed its presence in the water at Willow Springs.
The state Health Department does test swimming beaches for the presence of fecal coliforms, which can cause gastrointestinal distress. While the odds of contracting PAM are about 1 in 33 million, Haselow said, people are "many thousands of times" more likely to be sickened by fecal bacteria.
Haselow said if parents have a child "who can't get in water without being overly vigorous," he would recommend they choose a chlorinated pool for swimming. The amoeba can live in low concentrations of chlorine, but not what would be found in a public pool. Willow Springs was chlorinated, but had a sandy bottom.
"Recreational water users should assume that there is a low level of risk when entering all warm freshwater, particularly in southern-tier states," the CDC says.
Heulitt said it's theorized that some people may have a genetic malformation in the sinuses that makes them more vulnerable to the passage of the amoeba.