title: Elimination of Naegleria fowleri from bulk water and biofilm in an operational drinking water distribution system.
abstract: Global incidence of primary amoebic meningoencephalitis cases associated with domestic drinking water is increasing. The need for understanding disinfectant regimes capable of eliminating the causative microorganism, Naegleria fowleri, from bulk water and pipe wall biofilms is critical. This field study demonstrated the successful elimination of N. fowleri from the bulk water and pipe wall biofilm of a persistently colonised operational drinking water distribution system (DWDS), and the prevention of further re-colonisation. A new chlorination unit was installed along the pipe line to boost the free chlorine residual to combat the persistence of N. fowleri. Biofilm and bulk water were monitored prior to and after re-chlorination (RCl), pre-rechlorination (pre-RCl) and post-rechlorination (post-RCl), respectively, for one year. A constant free chlorine concentration of > 1 mg/L resulted in the elimination of N. fowleri from both the bulk water and biofilm at the post-RCl site. Other amoeba species were detected during the first two months of chlorination, but all amoebae were eliminated from both the bulk water and biofilm at post-RCl after 60 days of chlorination with free chlorine concentrations > 1 mg/L. In addition, a dynamic change in the biofilm community composition and a four log reduction in biofilm cell density occurred post-RCl. The pre-RCl site continued to be seasonally colonised by N. fowleri, but the constant free chlorine residual of > 1 mg/L prevented N. fowleri from recolonising the bulk and pipe wall biofilm at the post-RCl site. To our knowledge, this is the first study to demonstrate successful removal of N. fowleri from both the bulk and pipe wall biofilm and prevention of re-colonisation of N. fowleri in an operational DWDS. The findings of this study are of importance to water utilities in addressing the presence of N. fowleri and other amoeba in susceptible DWDSs.
authors.affiliation: CSIRO Land and Water, Private Bag No.5, Wembley, Western Australia 6913, Australia; School of Pathology and Laboratory Medicine, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.
authors.forename: Haylea C
authors.initials: HC
authors.lastname: Miller
authors.affiliation: CSIRO Land and Water, Black Mountain Laboratories, P.O. Box 1700, Canberra, ACT 2601, Australia.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Morgan
authors.affiliation: CSIRO Land and Water, Private Bag No.5, Wembley, Western Australia 6913, Australia.
authors.forename: Jason T
authors.initials: JT
authors.lastname: Wylie
authors.affiliation: CSIRO Land and Water, Private Bag No.5, Wembley, Western Australia 6913, Australia; School of Pathology and Laboratory Medicine, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.
authors.forename: Anna H
authors.initials: AH
authors.lastname: Kaksonen
authors.affiliation: School of Pathology and Laboratory Medicine, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Sutton
authors.affiliation: Water Corporation of Western Australia, 629 Newcastle Street, Leederville, Western Australia 6007, Australia.
authors.forename: Kalan
authors.initials: K
authors.lastname: Braun
authors.affiliation: CSIRO Land and Water, Private Bag No.5, Wembley, Western Australia 6913, Australia. Electronic address: Geoffrey.puzon@csiro.au.
authors.forename: Geoffrey J
authors.initials: GJ
authors.lastname: Puzon
mesh_terms: D018441:Biofilms; D004202:Disinfectants; D060766:Drinking Water; D054879:Halogenation; D016848:Naegleria fowleri
chemical_list: D004202:Disinfectants; D060766:Drinking Water
keywords: Amoeba; Biofilm; Chlorine; Drinking water distribution system; Naegleria fowleri