Background Naegleria fowleri is a climate-sensitive, thermophilic ameba found in warm, freshwater lakes and rivers. Primary amebic meningoencephalitis (PAM), which is almost universally fatal, occurs when N. fowleri–containing water enters the nose, typically during swimming, and N. fowleri migrates to the brain via the olfactory nerve. In August 2013, a 4-year-old child died of meningoencephalitis of unknown etiology in a Louisiana hospital. Methods Clinical and environmental testing and a case investigation were initiated to determine the cause of death and to identify potential exposures. Results Based on testing of CSF and brain specimens, the child was diagnosed with PAM. His only reported water exposure was tap water; in particular, tap water that was used to supply water to a lawn water slide on which the child had played extensively prior to becoming ill. Water samples were collected from both the home and the water distribution system that supplied the home and tested; N. fowleri were identified in water samples from both the home and the water distribution system. Conclusions This case is the first reported PAM death associated with culturable N. fowleri in tap water from a U.S. treated drinking water system. This case occurred in the context of an expanding geographic range for PAM beyond southern tier states with recent case reports from Minnesota, Kansas, and Indiana. This case also highlights the role of adequate disinfection throughout drinking water distribution systems and the importance of maintaining vigilance when operating drinking water systems using source waters with elevated temperatures.
Naegleria fowleri (N. fowleri) is a free‐living, trophic amoeba that is nearly ubiquitous in the environment and can be present in high numbers in warm waters. It is the causative agent of primary amoebic meningoencephalitis (PAM), a rare but particularly lethal disease with a very low survival incidence. Although N. fowleri was isolated from drinking water supplies in Australia in the 1980s, it was not considered a drinking water threat in the United States until recent cases were associated with a groundwater system in Arizona and surface water systems in Louisiana. N. fowleri in drinking water treatment and distribution systems can be managed using disinfectant concentrations typically encountered in well‐run plants although nitrification and attendant low disinfectant residuals may pose a challenge for some systems. The greatest challenge for N. fowleri control is in premise plumbing systems where conditions are largely outside the control of utilities, residuals might be low or nonexistent, and where water temperatures could be high enough to support rapid growth of the amoebae. This article reviews published studies describing the environmental occurrence, survival, pathogenicity, and disinfection of N. fowleri. In addition, this article provides information about this little known and poorly understood parasite with respect to its occurrence in the environment; how the amoeba amplifies in water systems such that it can cause infection; how N. fowleri has been successfully controlled for decades in water systems through treatment and distribution system management in Australia; and the knowledge gaps and information needed to address N. fowleri as an emerging pathogen in US water supplies.
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