Title: Legionella pneumophila vs. Legionella species for routine monitoring
Attendees will learn that focusing routine Legionella monitoring on Legionella pneumophila can maximize public health outcomes and minimize Legionella risk for their customers.
Jeff Bates, Product Manager, IDEXX
Adam Green, Baker Donelson
Reducing Legionella risk is a key objective for many water treaters. Helping building owners design and maintain water systems to minimize possible cases of Legionnaires’ disease is valuable for both risk management and public health. Routine monitoring for Legionella is increasingly accepted as an important component of water management plans for reducing Legionella risk, but there is ongoing debate on whether monitoring for Legionella species or Legionella pneumophila is more effective.
Recent research and scientific discussion are increasingly aligning on L. pneumophila as the target of choice. In a recent National Academies of Science, Engineering, and Medicine (NASEM) discussion of their consensus study on Legionella, all panelists agreed that targeting L. pneumophila for routine monitoring is supported by the current science. Recent studies by Hartemann (2018), and Walker and McDermott (accepted for publication) also support focusing routine testing on L. pneumophila.
A critical component of this debate is to identify the primary cause of Legionnaires’ disease. Based on a review of available data, it is clear that L. pneumophila is the pathogen of concern. In the US, only 0.3% of outbreaks reported on the National Outbreak Reporting System dashboard since 2009 identify a non-pneumophila Legionella species as the cause of an outbreak. In other countries, clinical cases of Legionnaires’ disease are confirmed via culture. Data from the European Center for Disease Control show that a minimum of 97% of culture-confirmed cases were caused by L. pneumophila. A recent study by Beaute et. al. (2020) confirms these numbers, independent of pre-selection bias associated with clinical screening tests. Research into the virulence factors of different Legionella species also shows that L. pneumophila is more virulent than non-pneumophila species.
The effectiveness of focusing routine monitoring on L. pneumophila has also been demonstrated in practice. There are multiple examples of localities focusing regulated Legionella testing on L. pneumophila. Data from these efforts illustrates that testing specifically for L. pneumophila has been effective in reducing Legionnaires’ disease case rates as well as the risk of cooling tower outbreaks. Since Quebec mandated routine testing for L. pneumophila, the number of cooling towers with contamination above the action limits has dropped by 50%. Additionally, Legionnaires’ disease cases in France, which requires monitoring specifically for L pneumophila, increased at only half the rate of Legionnaires’ disease case increases across Europe between 2013 and 2017.
It is important to highlight that there are notable exceptions, where it may be important to monitor for all Legionella species. Data shows that he majority of Legionnaires’ disease caused by non-pneumophila Legionella species occurs in severely immunocompromised individuals. Monitoring programs in buildings or wards with high populations of immunocompromised individuals, such as Intensive Care Units or areas with oncology or transplant patients, may decide to focus routine monitoring on all Legionella species.
The scientific community is increasingly aligning on L. pneumophila as the most appropriate target for routine monitoring to reduce Legionella risk. This session will enable water treaters to confidently employ this strategy to reduce risk and maximize public health outcomes.
Jeff Bates is the Product Manager for IDEXX Water’s Building Water Testing Solutions, which include fast, easy, and accurate tests for Legionella pneumophila and Pseudomonas aeruginosa. Since joining IDEXX Jeff has focused on the public health challenges associated with premise plumbing systems, especially in light of recent changes in building usage. Jeff has a B.A. in Environmental Studies from Middlebury College and an MBA from the Darden School of Business at the University of Virginia.
Mr. Green concentrates his practice in matters involving water handling systems, water treatment chemistry, products liability, commercial litigation, construction and toxic torts on a national scale. He has served as lead counsel in more than 25 states from Hawaii to Florida to Massachusetts.