Observations from the NSF/NSF conference:
Managing Legionella in Building Water Systems.
May 9-11, 2018 Baltimore MD.
This is a high interest topic – over 450 people attended the program presented by NSF International and the National Science Foundation.
Speakers included relevant US, Canadian, and European government agencies, microbiologists, plumbing and architectural engineers, legionella testing laboratories, university and industry researchers, and industrial and environmental safety professionals,
There are currently 8 US legionella control guidelines and voluntary standards.
NSF International is currently working on another standard (NSF 444) that will incorporate a prior NSF cooling tower guideline (NSF P453-2017).
New York State adopted a portion of ASHRAE 188 into a regulation that requires registration of all cooling towers and legionella testing every 90 days – thus making the NY regulation a potential legal standard of care across the country.
Garland Texas also has a Legionella ordinance.
In my opinion, direct legionella testing of water systems will be used to validate control measures in the future, and the culture method will be replaced by molecular and other techniques.
Only the current AIHA legionella guide “Recognition, Evaluation, and Control of Legionella in Building Water Systems” 2015 uses legionella testing to validate whether control measures are adequate. Most other guidelines validate with indirect tests such as temperature and disinfectant level.
WHO Drinking Water Parameter Cooperation Project – September 2017.
Support to the revision of Annex I Council Directive 98/83/EC on the Quality of Water Intended for Human Consumption (Drinking Water Directive). Introducing specific requirements for prevention and control of Legionella proliferation in warm drinking-water installations in priority buildings. Legionella causes a significant health burden in the EU and the highest health burden of all waterborne pathogens. Thereby, addressing Legionella in the Directive would present a significant step in protecting the health of EU citizens. We specifically recommend including requirements for risk-based evaluation of drinking-water installations in priority buildings, operational monitoring of temperature (see also point 2 above), verification monitoring of Legionella in Annex I Part A with a trigger value which is intended to prompt risk-based responses. Details of these proposals are provided in Chapters 6 and 7, as well as in the corresponding Legionella fact sheet in Appendix 3.
Distribution of Legionella and bacterial community composition among regionally diverse US cooling towers – December 2017 .
Cooling towers (CTs) are a leading source of outbreaks of Legionnaires’ disease (LD), a severe form of pneumonia caused by inhalation of aerosols containing Legionella bacteria. Accordingly, proper maintenance of CTs is vital for the prevention of LD. The aim of this study was to determine the distribution of Legionella in a subset of regionally diverse US CTs and characterize the associated microbial communities. Between July and September of 2016, we obtained aliquots from water samples collected for routine Legionella testing from 196 CTs located in eight of the nine continental US climate regions. After screening for Legionella by PCR, positive samples were cultured and the resulting Legionella isolates were further characterized. Overall, 84% (164) were PCR-positive, including samples from every region studied. Of the PCR-positive samples, Legionella spp were isolated from 47% (78), L. pneumophila was isolated from 32% (53), and L. pneumophila serogroup 1 (Lp1) was isolated from 24% (40). Overall, 144 unique Legionella isolates were identified; 53% (76) of these were Legionella pneumophila. Of the 76 L. pneumophila isolates, 51% (39) were Lp1. Legionellawere isolated from CTs in seven of the eight US regions examined. 16S rRNA amplicon sequencing was used to compare the bacterial communities of CT waters with and without detectable Legionella as well as the microbiomes of waters from different climate regions. Interestingly, the microbial communities were homogenous across climate regions. When a subset of seven CTs sampled in April and July were compared, there was no association with changes in corresponding CT microbiomes over time in the samples that became culture-positive for Legionella. Legionella species and Lp1 were detected frequently among the samples examined in this first large-scale study of Legionella in US CTs. Our findings highlight that, under the right conditions, there is the potential for CT-related LD outbreaks to occur throughout the US.