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A deadly waterborne amoeba that can get into the brain and kill has been found again in tap water in the New Orleans area, state health officials said Thursday.

They’ve found Naegleria fowleri in St. Bernard Parish, a coastal suburb of New Orleans that was devastated 10 years ago by Hurricane Katrina.

In 2013, the one-celled organism killed a 4-year-old Mississippi boy who likely got it playing on a back yard Slip 'N Slide. Tests showed it was living in under-chlorinated tap water in the system. Officials cleaned and flushed the system at the time, but it’s back, the state Department of Health and Hospitals said.

“DHH Safe Drinking Water Program staff sampled seven sites along the St. Bernard Parish Water System. Two of the seven sites tested positive for the amoeba,” the department said in a statement.

"Two of the seven sites tested positive for the amoeba."

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“One positive test was at a site at the water treatment plant before the water was treated. The second positive test occurred at 948 Angela Street, which may have been contaminated by ground water due to a leak at the sampling station. Chlorine levels at the site of the positive sample did meet the 0.5 mg/l requirement.”

The health department's Olivia Hwang says officials are putting extra chlorine into the water. She said a car hit the sampling station, causing damage and possibly allowing untreated groundwater to leak into the water supply.

Chlorination kills the amoeba, which can multiply in warm water. It’s often found in lakes and rivers. It killed a Minnesota teenager earlier this month.

"There are a number of parts of St. Bernard parish that still don’t have the same levels of population since Hurricane Katrina," she said. That means less water gets used. "Use is good because it pushes new water through the system," she added.

If fresh water is not continually flushed through pipes, the water can sit and become warm and contaminated.

N. fowleri is usually harmless unless it gets up someone’s nose. It’s not entirely clear how or why, but in rare instances it can attach to one of the nerves that takes smell signals to the brain. There, the amoeba reproduces and the brain swelling and infection that follows is almost always deadly.

"The Department urges residents to avoid getting water in their noses."

It doesn’t hurt people who swallow water.

“Tap water in St. Bernard Parish is safe for residents to drink, but the Department urges residents to avoid getting water in their noses,” Louisiana’s health department said.

“DHH conducts sampling of public drinking water systems for Naegleria fowleri each summer when temperatures rise. So far, DHH has tested 12 other systems for the ameba and still awaiting lab results for each.”

The department has some advice for residents while it re-treats the water system: