Legionnaires' Disease: Are We Testing for the Right Things?
The severe pneumonia called Legionnaires' disease has long been a public health concern, but recent research from the University of Michigan suggests that testing for more than one strain of Legionella pneumophila may help widen the net of treatment.
Two late-2024 studies highlight critical gaps in current testing and water treatment strategies, emphasizing the need for a more comprehensive approach to detecting and mitigating Legionella contamination.
The Hidden Threat in Residential Water Systems
One of the studies found that the strain of Legionella bacteria most commonly present in homes is not the one that doctors typically test for. Currently, most testing is for Legionella pneumophila serogroup 1 (Sg1), but the first Legionella bacteria detected in Flint, Michigan, was Legionella pneumophila serogroup 6 (Sg6).
Legionella pneumophila Sg6 is usually not tested for in hospitals, because it requires a slower form of diagnosis. This revelation raises concerns about the accuracy of current diagnostic methods, as patients suffering from Legionnaires' disease may go undiagnosed if their infection is caused by a strain that standard tests fail to detect.
Legionella bacteria thrive in warm water environments, making residential plumbing systems a prospective breeding ground. However, researchers are still determining whether Legionella pneumophila Sg6 can survive in aerosols, the tiny water droplets that Legionella pneumophila Sg1 bacteria are known to thrive in. Such droplets—from a shower, for instance—are the main way Legionella gets into the lungs.
The study suggests that expanding testing protocols to include a broader range of Legionella strains could potentially improve detection rates and ensure timely treatment for patients.
Corroded Pipes and the Weakening of Chlorine's Defense
The second study from the University of Michigan explored the impact of corroded pipes on water treatment effectiveness. Researchers discovered that as pipes corrode in older buildings, they release iron and organic matter into the water, creating an environment where Legionella bacteria can thrive. At the same time, these contaminants weaken the disinfecting power of chlorine, making it less effective at killing the bacteria in municipal water systems.
Many systems also use other water-treatment chemicals to protect pipes from corrosion, which can release iron, lead, and other metals into the water. These new results show the importance of careful water monitoring and treatment everywhere.
The Case for Enhanced Testing and Infrastructure Improvements
Current diagnostic methods focus primarily on Legionella pneumophila Sg1, but expanding testing to include other strains could lead to more accurate diagnoses and better patient outcomes. Additionally, addressing pipe corrosion through infrastructure upgrades and alternative disinfection methods could strengthen efforts to control Legionella contamination.
By refining testing protocols and investing in water system improvements, communities can reduce the risk of Legionella-related illnesses and ensure safer drinking water for all.
Moving Forward: A Call to Action
Legionnaires' disease remains a serious health threat, and outdated testing methods and deteriorating infrastructure only exacerbate the problem. By taking steps to expand Legionella testing and monitoring, we can move toward a future where Legionnaires' disease is more effectively detected and prevented, ensuring safe environments for everyone.
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