Photograph by Tyrone Turner, National Geographic

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Traces of a brain-eating amoeba have been found in New Orleans' St. Bernard Parish's water supply.

Photograph by Tyrone Turner, National Geographic

Brain-Eating Amoeba in Louisiana Linked to Hurricane Katrina?

Tap water became a breeding ground for a deadly amoeba, experts speculate.

The deadly brain-eating amoeba that recently killed a four-year-old Louisiana boy may be linked to unsafe water conditions created by Hurricane Katrina in 2005, experts say.

The boy, Drake Smith Jr., died from a rare but deadly swelling of the brain caused by Naegleria fowleri, a species of single-celled organism known as an amoeba. (Related: "What We Do—and Don't—Know About Brain-Eating Amoebas.")

The child was playing on a backyard Slip 'n Slide in St. Bernard Parish, near New Orleans, and was apparently infected by amoebae present in the water in early August. About two days later, he was dead.

For N. fowleri to gain access to the brain, it must go up a person's nose and climb the olfactory nerve. Simply drinking water that contains the amoeba is not enough to cause an infection, said Raoult Ratard, Louisiana's state epidemiologist.

"[The boy] spent all day on the slide," he said. "I wouldn't be surprised if some water went up his nose."

N. fowleri is commonly found in lakes and other freshwater systems, but is usually not considered a danger to swimming pools or municipal water systems because they are typically treated with chlorine or other types of disinfectants that kill the amoeba.

Sitting in the Sun

But St. Bernard Parish was devastated when Katrina struck in August 2005. "St. Bernard was under 15 feet of floodwater. Water pipes were broken, and the [water] pressure was zero," said Jake Causey, chief engineer for the Louisiana Department of Health and Hospitals.

People fled St. Bernard Parish after the hurricane, and the town's population shrank from about 67,000 people to about 35,000, Causey said.

The depopulation left a lot of vacant homes and buildings where water just sat in the sun for years.

According to Ratard, studies have shown that summer heat can destroy the residual chlorine that is added to municipal water. Without the chlorine to keep N. fowleri in check, "the amoeba would multiply," he said.

Water samples taken from the child's home and sent to the Centers for Disease Control and Prevention in Atlanta for testing contained evidence of N. fowleri contamination.

"The same [strain] of N. fowleri that was found in the child's brain tissue was found in the hose and in the water from the faucet in the yard," Ratard said.

Since the boy’s death last month, the amoeba has been found throughout the water supply system in St. Bernard Parish, which is located south of New Orleans.

"Just an Idea"

While the boy's death seems to have clearly been caused by N. fowleri present in his home's water supply, scientists say that definitively linking the amoeba to Hurricane Katrina will be difficult—if not impossible.

"My understanding is that this amoeba is pretty common in freshwater throughout the United States. As a scientist, I wouldn't necessarily support Katrina as a causation there," said Dawn Wesson, an epidemiologist at Tulane University in New Orleans, who was not involved in the investigation.

Ratard agreed. "It's just an idea," he said. "We might never know the answer."

Whether or not it's ever proved that St. Bernard's amoeba outbreak was the result of Katrina, scientists say that it is well established that natural disasters such as hurricanes can lead to increased incidence of various diseases such as cholera and tetanus.

A 2008 study by Wesson and her colleagues found that following Katrina, the incidence of mosquito-borne West Nile Virus infection doubled.

The scientists hypothesized at the time that the combination of power outages and the overall lack of services in the New Orleans region in the months following the hurricane caused many more people to be exposed to outdoor elements—such as mosquitoes—than would have normally been the case.

Disease outbreaks following natural disasters can be an especially dire problem in developing countries, Ratard said, where clean water and food and good sanitation may not always be readily accessible.

"After Katrina, what we saw was a lot of outbreaks in the shelters," he said. "Because all at once, thousands of people who were living in individual homes were crammed together in one big place."

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