By Kathy Finn
NEW ORLEANS (Reuters) - Some Louisiana towns intensified testing of water supplies on Monday after a 4-year-old boy died from a rare brain-eating amoeba that authorities suspect he contracted while playing on a Slip-N-Slide toy in the backyard of a home.
"We are testing and retesting our water to make sure it has the proper amount of chlorine to prevent contamination," said David Peralta, president of St. Bernard Parish, where the boy was visiting when he is believed to have become infected.
Local schools also remain on guard.
"Just to be cautious, we turned off the water fountains at the elementary and middle schools," said Doris Voitier, superintendent of St. Bernard Public Schools.
The Centers for Disease Control and Prevention confirmed in August that the amoeba Naegleria fowleri caused the early August death of the boy, a Mississippi resident who became mysteriously ill and died while visiting friends in St. Bernard Parish, which is southeast of New Orleans.
Tissue tests by the CDC later revealed the boy died from a form of encephalitis after the amoeba entered his body through his nose and attacked his brain.
Louisiana's Office of Public Health investigated circumstances leading to the boy's death and concluded that he may have become infected while playing on a Slip 'N Slide water toy in the backyard of the home he was visiting.
The Louisiana Department of Health and Hospitals on Friday confirmed the presence of the amoeba in four locations of the water system in St. Bernard Parish.
State epidemiologist Dr. Raoult Ratard said Naegleria fowleri infections are rare, though the amoeba itself is not. Studies have shown that the amoeba exists "in very low numbers" in about 40 percent of water supplies in the developed world, he said.
He said the amoeba likely multiplied in the St. Bernard water system because the chlorine level in some locations fell below the 0.5 milligrams per liter standard by the CDC. Ratard said humans are infected through the nose and not from drinking.
From 2001 to 2010, 32 Naegleria fowleri infections were reported in the United States. Of those cases, 30 people were infected by contaminated recreational water and two by water from a geothermal drinking water supply, according to the CDC.
Peralta said that St. Bernard Parish is continuing to flush its water system and add chlorine to ensure that the water is safe for drinking and bathing.
While communities that lie near St. Bernard Parish have their own, separate water supplies, some are seeking assurances that their water is safe.
Plaquemines Parish President Billy Nungesser said parish employees flushed the water lines over the weekend and he has asked the state health department to test the parish's water system. "The steps we are taking are purely precautionary measures," he said in a release on Friday.
(Reporting by Kathy Finn; Editing by Greg McCune and Leslie Adler)