Occurrence of Naegleria fowleri in Arizona drinking water supply wells

Naegleria fowleri is a protozoan found naturally in hot springs and warm surface waters. It can cause usually lethal primary amoebic meningoencephalitis. The goal of this study was to determine the occurrence of N. fowleri in drinking water supply wells in Arizona. Nested polymerase chain reaction was used to detect trophozoites and cysts, but not to assess viability. A total of 185 samples were collected from 113 wells before disinfection. The presence of N. fowleri deoxyribonucleic acid was confirmed in 10.6% of wells. No correlations were found between the presence of N. fowleri and heterotrophic bacteria, coliforms, Escherichia coli, temperature, specific conductance, or turbidity. N. fowleri was detected in 10.0% of initial and 17.2% of purged well samples, suggesting that N. fowleri may be present in the aquifer or detach from the well casing or pump column during pumping.