Rapid Rise in Legionnaires’ Disease Infections As Air Pollution Decreases

MedicalResearch.com Interview with:

Dr. Fangqun Yu

Dr. Fangqun Yu

Dr. Fangqun Yu PhD
Senior Research Faculty
Atmospheric Sciences Research Center University
Albany, State University of New York


Dr. Arshad Arjunan Nair

Dr. Arshad Nair

Dr. Arshad Arjunan Nair PhD
Postdoctoral Associate
Atmospheric Sciences Research Center
University at Albany, State University of New York


MedicalResearch.com: What is the background for this study? What are the main findings?

Dr. Fangqun Yu: Legionnaires’ disease is a severe form of pneumonia with a fatality rate of 10-25% caused by inhaling or aspirating Legionella, bacteria that thrive in built environment water systems. Those most vulnerable to this disease are male, over 50 years of age, have a history of smoking, have chronic respiratory diseases, diabetes, are immunocompromised, and/or minorities. The US observed a nearly nine-fold increase in Legionnaires’ disease between 2000 and 2018, with New York State having one of the highest increases in disease rates. The reasons for the increase in incidence were unclear prior to this study.

In our study, we found:

(1) Declining sulfur dioxide concentrations (SO2) are strongly correlated with the increase in legionellosis cases and a physical mechanism explaining this link is proposed,

(2) A geostatistical epidemiological analysis links the disease with exposure to cooling towers, and

(3) Climate and weather are ruled out as factors responsible for the long-term increase in case numbers (outside of seasonal trends).

MedicalResearch.com: What should readers take away from your report?

Dr. Arshad Nair:  Our work that mechanistically links decreasing atmospheric SO2 with Legionnaires’ disease can have implications for a better understanding of its transmission, predicting future risks, and informed design of preventive and interventional strategies. While this work highlights the need to holistically consider the complexities of continued SO2 changes, it would be unwise to argue against its reductions, which have other well-recognized and larger overall health benefits.

Readers should recognize the complex balance between environmental gains and unforeseen emerging public health challenges. Stakeholders, including public health officials and clinicians, should be aware of the potentially increased risk for legionellosis during periods of high cooling tower use and low SO2, targeting at-risk populations in areas of chronically high incidence. Knowledge of this risk may improve diagnostic and treatment decisions surrounding cases of community-acquired pneumonia, of which Legionella are increasingly recognized as a cause of.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Dr. Fangqun Yu: The present study is the first of its kind in connecting Legionnaires’ disease with air quality, and the analysis focuses largely on the state of New York. It is our hope that this study will stimulate more research on this disease and its connection with environmental factors, including air quality.

Firstly, expanding this analysis beyond New York State could establish the connection more robustly between cooling towers, SO2 levels, and Legionnaires’ disease.

Secondly, while the largest impacts on aerosol acidity are expected to be from SO2, the possible impacts from other pollutants such as ammonia and nitric acid, should be investigated.

Thirdly, laboratory measurements are needed to systematically evaluate the survival of Legionella in contaminated droplets under various relevant atmospheric conditions. Finally, if the findings of this work are confirmed through further studies, strategies to better control Legionella and mitigate exposure risk need to be designed, tested, and implemented.

MedicalResearch.com: Is there anything else you would like to add? Any disclosures?

Dr. Arshad Nair:  Addressing complex real-world problems increasingly demands transdisciplinary research that is use-inspired. Although challenging, such collaborations that cut across scientific disciplines and foster the engagement of varied stakeholders hold immense potential for building our community’s climate and health resilience.

Disclosure: This study was supported under an award to the State University of New York at Albany from the New York State Energy Research and Development Authority (NYSERDA) for energy-related air quality and health effects research.

Citation: Fangqun Yu, Arshad A Nair, Ursula Lauper, Gan Luo, Jason Herb, Matthew Morse, Braden Savage, Martin Zartarian, Meng Wang, Shao Lin, Mysteriously rapid rise in Legionnaires’ disease incidence correlates with declining atmospheric sulfur dioxide, PNAS Nexus, Volume 3, Issue 3, March 2024, pgae085, https://doi.org/10.1093/pnasnexus/pgae085


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Last Updated on March 14, 2024 by Marie Benz MD FAAD