Experts say the only danger is to people who manage to get the microscopic organism way up their noses. Its only entry to the brain is through tiny openings in a bone about level with the top of the eyeball, said Dr. Raoult Ratard, Louisiana's state epidemiologist.
The state Department of Health and Hospitals on Thursday tried to dispel common "myths and rumours" about the amoeba Naegleria fowleri starting with the notion that the St. Bernard Parish water isn't safe to drink.
Jonathan Yoder, an epidemiologist in the Centre for Disease Control and Prevention's waterborne disease prevention branch, said Naegleria has never before been found in water treated by a US water system.
There have been 132 documented infections from the amoeba since 1962, almost all of them fatal, health officials say.
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Both of Louisiana's 2011 infections were of people who used tap water to flush out their sinuses. In those cases, Yoder said the amoeba was found in the house's hot water system but not in municipal water or water coming from the home's cold water tap. But still, people worry.
That's not necessary, experts say. Stomach acids, boiling and chlorine all will kill the amoeba. Investigators may never know just how Naegleria got into the pipes.