Louisiana health officials traced a rare but fatal brain infection that killed a 4-year-old boy in August to the tap water in St. Bernard Parish, southeast of New Orleans. It's the first time the amoeba, called Naegleria fowleri, has ever been found in a treated water supply.
“From a U.S. perspective this is a unique situation,” Dr. Michael Beach, head of water safety for the CDC, told Time. But NBC reports that the unique conditions brought about by Hurricane Katrina may help to explain how it got there:
Dr. Raoult Ratard, the Louisiana state epidemiologist, says the devastation wrought by Hurricane Katrina in August 2005 may ultimately be to blame. Low-lying St. Bernard Parish -- where the boy Drake Smith Jr. from Mississippi was infected while playing on a Slip ‘N Slide in a backyard in the Parish -- was badly hit by the flooding that Katrina caused.
“After Katrina, it almost completely depopulated,” Ratard told NBC News. “You have a lot of vacant lots and a lot of parts of the system where water is sitting there under the sun and not circulating.”
That, says Ratard, provided a perfect opportunity for the amoeba to multiply. Without enough chlorine to kill them, they can spread.
The CDC, however, did not back up Ratard's claim.
Officials are responding by adding more chlorine to the water, which health officials say is safe to drink. The amoeba only poses a risk when it makes contact with a victim's brain -- usually by getting all the way up their nose. So people are advised not to snort the water, and to refrain from putting their heads under bath water that hasn't been chlorinated.
“As long as you know the top of your nose and where is the top of your nose, and where is the bottom of your nose, you will be all right,” Ratard told reporters.
Still, that the amoeba is there at all is "troubling and noteworthy," writes NPR's Richard Knox. Previous cases -- as with the two 12-year-olds who were infected this summer -- only occurred in freshwater. But Knox points out that two Louisiana residents died in 2011 after they sent water up their noses with a neti pot. In that case, health officials assumed, but were never able to prove, that contaminated water caused the infection.
Some experts warn, too, that Naegleria fowleri infections could be becoming more common. As Jonathan Yoder, a CDC epidemiologist, told National Geographic earlier this summer: "What has changed recently is that cases have appeared in places we had never seen before—like Minnesota, Indiana, and Kansas. This is evidence that the amoeba is moving farther north. In the past it was always found in warmer weather states."