On July 22, the Louisiana Department of Health & Hospitals issued a warning to residents in St. Bernard Parish about the discovery of Naegleria fowleri in drinking water in the Parish. The brain-eating amoeba was discovered by state testing in two places. The local water authority has been told to conduct a chlorine “burn”, increase the chlorine levels in the drinking water, to remove the threat.
Naegleria fowleri is an amoeba that lives in warm, fresh water, according to the Centers for Disease control and Prevention (CDC). The microscopic organism is responsible for primary amebic meningoencephalitis (PAM), a rare, and very serious infection. The illness is usually contracted by patients who have water up their nose through swimming or other water activities. The CDC states that it cannot be caught through drinking water. PAM is almost always fatal.
A 2003 study of the water systems Arizona homes where two children died from PAM found that the amoeba was widely dispersed, in areas of the plumbing where the water could stand and become warm. Neither child had a history of exposure to any lakes or rivers, and both children routinely played in the bath tub.
Another study, published in 2015, looked at the death of a four year old in Louisiana from PAM. This boy had no history of playing in fresh water but was a frequent user of a water slide at his home. Samples from both the home and its water supply found N. fowleri.
The CDC notes that several cases of PAM resulted from colonization of public water systems by N. fowleri. One large cluster was found in Australia where long pipe runs and inadequate disinfection of the water allowed the amoeba to find a home in the system. A small number of cases have been linked to the use of tap water in neti pots or for nasal rinsing. Most illnesses, however, are linked to the patient’s exposure in fresh water lakes and streams.
The disease is rare, extremely rare. The CDC reports 133 cases of primary amebic meningoencephalitis in the period 1962-2014. The amoeba has also been isolated in autopsy samples dated as long ago as 1937.
Demographics for the 133 patients are noteworthy. Children have contracted 112 of the infections, 84 percent. Over 75 percent of the 133 infections were in male patients. “Infected people were often reported to have participated in water-related activities such as swimming underwater, diving, and head dunking that could have caused water to go up the nose.”
The Louisiana Department of Health & Hospitals offers several suggestions for preventing an infection by Naegleria fowleri. The most important, stressed in several different ways, is to avoid getting untreated water up the nose. People who use neti posts or perform nasal rinses should use only distilled or sterile water. Children’s water toys such as wading pools should be emptied and scrubbed after each use. Chlorine levels in swimming pools and hot tubs should be kept at levels that will disinfect the water.
The disease is very rare. The likelihood of infections is extremely low but it is not zero. Preventive steps can be taken with little additional cost or effort.