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Your Garden Hose: A potential health risk due to Legionella spp. growth facilitated by free-living amoebae
Thomas, J., T. Thomas, R. Stuetz, AND N. Ashbolt. Your Garden Hose: A potential health risk due to Legionella spp. growth facilitated by free-living amoebae. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 48(17):10456-10464, (2014).
To inform the public.
Common garden hoses may generate aerosols of inhalable size (<10 um) during use. If aerosols are inhaled containing Legionella bacteria, Legionnaires' disease or Pontiac fever may result. Noting clinical cases have been linked to garden hose use. The hose environment is ideal for the growth and interaction of legionella and free-living amoebae (FLA) due to biofilm formation, elevated temperatures and stagnation of water. However, the microbial densities and hoses conditions necessary to quantify the human health risks have not been reported. Here we present data on FLA and Legionella spp. detected in water and biofilm of two garden hose types over 18 months. By culturing and qPCR, two genera of FLA were introduced via the supplying drinking water and reach mean densities of 2.5 log10 amoebae.mL-1. in garden hose water. Legionella spp. densities (included likely pathogenic pathogenic L. pneumophila) were significantly higher in one hose type (3.8 log10 cells.mL-1, p<0.0001). A positive correlation existed between Vermamoebae vermiformis densities and Legionella spp. densities (r=0.83, p<0.028). The densities of Legionella spp. identified in the hoses were similar to those reported during legionellosis outbreaks in other situations. Therefore we conclude that there is a health risk to susceptible users fom the inhalation of garden hose aerosols.