AUTHOR=Brigmon Robin L. , Turick Charles E. , Knox Anna S. , Burckhalter Courtney E. 

TITLE=The Impact of Storms on Legionella pneumophila in Cooling Tower Water, Implications for Human Health

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.543589

DOI=10.3389/fmicb.2020.543589

ISSN=1664-302X

ABSTRACT=<p>At the U.S. Department of Energy’s Savannah River Site (SRS) in Aiken, SC, cooling tower water is routinely monitored for <italic>Legionella pneumophila</italic> concentrations using a direct fluorescent antibody (DFA) technique. Historically, 25–30 operating SRS cooling towers have varying concentrations of <italic>Legionella</italic> in all seasons of the year, with patterns that are unpredictable. Legionellosis, or Legionnaires’ disease (LD), is a pneumonia caused by <italic>Legionella</italic> bacteria that thrive both in man-made water distribution systems and natural surface waters including lakes, streams, and wet soil. Legionnaires’ disease is typically contracted by inhaling <italic>L. pneumophila</italic>, most often in aerosolized mists that contain the bacteria. At the SRS, <italic>L. pneumophila</italic> is typically found in cooling towers ranging from non-detectable up to 10<sup>8</sup> cells/L in cooling tower water systems. Extreme weather conditions contributed to elevations in <italic>L. pneumophila</italic> to 10<sup>7</sup>–10<sup>8</sup> cells/L in SRS cooling tower water systems in July–August 2017. <italic>L. pneumophila</italic> concentrations in Cooling Tower 785-A/2A located in SRS A-Area, stayed in the 10<sup>8</sup> cells/L range despite biocide addition. During this time, other SRS cooling towers did not demonstrate this <italic>L. pneumophila</italic> increase. No significant difference was observed in the mean <italic>L. pneumophila</italic> mean concentrations for the towers (<italic>p</italic> &lt; 0.05). There was a significant variance observed in the 285-2A/A Tower <italic>L. pneumophila</italic> results (<italic>p</italic> &lt; 0.05). Looking to see if we could find “effects” led to model development by analyzing 13 months of water chemistry and microbial data for the main factors influencing the <italic>L. pneumophila</italic> concentrations in five cooling towers for this year. It indicated chlorine and dissolved oxygen had a significant impact (<italic>p</italic> &lt; 0.0002) on cooling tower 785A/2A. Thus, while the variation in the log count data for the A-area tower is statistically greater than that of the other four towers, the average of the log count data for the A-Area tower was in line with that of the other towers. It was also observed that the location of 785A/2A and basin resulted in more debris entering the system during storm events. Our results suggest that future analyses should evaluate the impact of environmental conditions and cooling tower design on <italic>L. pneumophila</italic> water concentrations and human health.</p>