ADVANCEMENT OF THE SCIENCE
Conclusion We identified a cooling tower as the potential direct and indirect source for at least five cases of LD in an outbreak investigation spanning a 2-year period. In 2019, cooling tower E was genetically linked to four cases. In 2021, iso- lates recovered from an outdoor hot tub and a clinical specimen were found to be geneti- cally similar to 2019 environmental and clini- cal samples, indicating that closely related Legionella strains (1–2 SNPs) persisted in this community for approximately 2 years. The cooling tower could have seeded the hot tub in 2019. The cooling tower has since been removed and replaced with a glycol system, which does not require water. These findings could have bigger-picture implications and help inform our understanding of the persis- tence of Legionella in communities and how exposures occur. The U.S. continues to see an increase in LD cases, and the reason for the increase is likely multifactorial. Case questionnaires that reveal local travel history and various water exposures of cases are essential. Ruling out additional sources, such as the residences of LD cases, should continue to be explored. A recent sampling study (2020–2021) of single- family homes in New Jersey found that out of 94 homes, 15% had at least one positive sam- ple for Legionella by culture and 57% had at least one sample with a detection of Legionella DNA markers by PCR (Gleason et al., 2023). The sheer volume of samples collected, the number of sources explored, and the eective collaboration between state and local gov- ernments can serve as a template for which environmental and epidemiological investi- gations of LD clusters and outbreaks should be modeled going forward. Acknowledgements: We would like to acknowledge the Bureau of Communicable Disease Control for performing the epide- miological functions and New York State Wadsworth Center laboratories for their work analyzing samples. CCHD set the standard for local health departments in responding to an outbreak of this magnitude. In addi- tion, we thank the Advanced Genomic Tech- nologies Cluster at the Wadsworth Center for whole genome sequencing and the Media, Glassware, and Tissue Culture Core facilities at the Wadsworth Center for media and buf- fers used for the bacterial cultures.
FIGURE 2
Frequency of Optimal Wind Direction per Genetically Similar 2019 Case of Legionnaires’ Disease in New York
0 1 2 3 4 5 6 7 8 9 10
SSW
SW
W SW
W i nd D i r ec ti on
Case 1
Case 2
Case 3
Case 4
Note. Figure 2 shows the percentage of time that wind blew from the south-southwest (SSW), southwest (SW), and west-southwest (WSW) directions during the estimated exposure window for the four Legionnaires’ disease cases that were found to be genetically similar to each other and genetically similar to the basin of cooling tower E in 2019. These directions were chosen using the location of cooling tower E and the residential addresses for the four patient cases. The exposure window was considered to be the 12 days between 2 and 14 days prior to reported symptom onset for each case; this length of time was chosen to capture the most accurate incubation period possible. Wind blowing from these directions was considered to be optimal for the LD cases to be exposed to the drift from cooling tower E. The percentage of time when optimal wind direction occurred was calculated to be between 9.29% (case 4) and 21.15% (case 1). Case 1 would appear to have had optimal wind direction occur the most and, therefore, potentially had the largest window for exposure. Weather data were supplied by New York State Mesonet from the nearest weather station. Data cleaning and grouping of wind directions was performed in Python 3.10, and figures were generated using Microsoft Excel.
The weather research was made possible by NYS Mesonet. Original funding for NYS Mesonet was provided by a Federal Emer- gency Management Agency grant (FEMA- 4085-DR-NY) with the continued support of the NYS Division of Homeland Security & Emergency Services; the state of New York; the Research Foundation for the State Uni- versity of New York (SUNY); the University at Albany, SUNY; the Atmospheric Sciences Research Center at SUNY Albany; and the Department of Atmospheric and Environ- mental Sciences at SUNY Albany. This publication was supported by Coop- erative Agreement Number NU50CK000516 funded by the Centers for Disease Control and Prevention. Its contents are solely the respon- sibility of the authors and do not necessarily represent the o¤cial views of the Centers for
Disease Control and Prevention or the U.S. Department of Health and Human Services. We would also like to acknowledge the fol- lowing individuals and sta who assisted in this investigation: Hyland Hartsough (West- ern Region NYSDOH); Neculai Codru, MS, MPH (NYSDOH); Peter Bozetti (CCHD); Brian Borowski, MS (NYSDOH); Jon Keough (CCHD); Theresa Hattenrath, PhD (Wad- sworth Center NYSDOH); NYSDOH Western Regional sta; and Wadsworth Center sta. Corresponding Author: Matthew Morse, Research Scientist, Water Systems Control and Analysis, Bureau of Water Supply Protec- tion, New York State Department of Health, Empire State Plaza, Corning Tower, Room 1772, Albany, NY 12237. Email: matthew.morse@health.ny.gov.
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Volume 86 • Number 9
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