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Environmental Research
Vol. 150, 2016, Pages: 320–327

Public health implications of Acanthamoeba and multiple potential opportunistic pathogens in roof-harvested rainwater tanks

K.A. Hamilton, W. Ahmed, A. Palmer, J.P.S. Sidhu, L. Hodgers, S. Toze, C.N. Haas

CSIRO Land and Water, Ecosciences Precinct, 41 Boggo Road, Qld 4102, Australia.


A study of six potential opportunistic pathogens (Acanthamoeba spp., Legionella spp.,Legionella longbeachaePseudomonas aeruginosaMycobacterium avium andMycobacterium intracellulare) and an accidental human pathogen (Legionella pneumophila) in 134 roof-harvested rainwater (RHRW) tank samples was conducted using quantitative PCR (qPCR). All five opportunistic pathogens and accidental pathogen Lpneumophila were detected in rainwater tanks except Legionella longbeachae. Concentrations ranged up to 3.1×106 gene copies per L rainwater forLegionella spp., 9.6×105 gene copies per L for P. aeruginosa, 6.8×105 gene copies per L for M. intracellulare, 6.6×105 gene copies per L for Acanthamoeba spp., 1.1×105 gene copies per L for M. avium, and 9.8×103 gene copies per L for L. pneumophila. Among the organisms tested, Legionella spp. (99% tanks) were the most prevalent followed by M. intracellulare (78%). A survey of tank-owners provided data on rainwater end-uses. Fecal indicator bacteria (FIB) Escherichia coli and Enterococcus spp. were enumerated using culture-based methods, and assessed for correlations with opportunistic pathogens and L. pneumophila tested in this study. Opportunistic pathogens did not correlate well with FIB except E. coli vs. Legionella spp. (tau=0.151, P=0.009) and E. colivs. M. intracellulare (tau=0.14, P=0.015). However, M. avium weakly correlated with bothL. pneumophila (Kendall’s tau=0.017, P=0.006) and M. intracellulare (tau=0.088,P=0.027), and Legionella spp. also weakly correlated with M. intracellulare (tau=0.128,P=0.028). The presence of these potential opportunistic pathogens in tank water may present health risks from both the potable and non-potable uses documented from the current survey data.

Keywords: Roof-harvested rainwater; Opportunistic pathogens; Fecal indicator bacteria; Quantitative PCR; Health risks; Rainwater survey.

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