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. 2022 Jan 20;19(3):1119.
doi: 10.3390/ijerph19031119.

A Community Outbreak of Legionnaires' Disease with Two Strains of L. pneumophila Serogroup 1 Linked to an Aquatic Therapy Centre

Cyril Rousseau  1 , Christophe Ginevra  2   3 , Leslie Simac  1 , Noel Fiard  4 , Karine Vilhes  4 , Anne-Gaëlle Ranc  2   3 , Sophie Jarraud  2   3 , Hervé Gornes  4 , Damien Mouly  1 , Christine Campese  5
Affiliations

A Community Outbreak of Legionnaires' Disease with Two Strains of L. pneumophila Serogroup 1 Linked to an Aquatic Therapy Centre

Cyril Rousseau et al. Int J Environ Res Public Health. .

Abstract

An outbreak of Legionnaires' disease affected 18 people in Montpellier, a town of the south of France, between December 2016 and July 2017. All cases were diagnosed by a positive urinary antigen test. No deaths were reported. Epidemiological, environmental and genomic investigations (nested Sequence-Based Typing (nSBT) and whole genome sequencing) were undertaken. For the cases for which we had information, four had a new isolate (ST2471), one had a different new isolate (ST2470), one had a genomic pattern compatible with the ST2471 identified by nSBT (flaA = 3), and one had a genomic pattern not compatible with two previous identified STs (pilE = 6). The analysis conducted on the pool of an aquatic therapy center revealed seven isolates of Legionella pneumophila. Whole genome analysis confirmed the link between the environmental and clinical isolates for both ST2470 and ST2471. As the outbreak occurred slowly, with several weeks between new cases, it was not possible to immediately identify a common source. The sixth case was the first to report having aquatic therapy care. Of the 18 cases, eight had attended the aquatic therapy center and the other 10 were inhabitants who lived, worked or walked close to the center. The main cause for this outbreak was the lack of facility maintenance. This investigation highlights the risk to public health of aquatic therapy centers for users and nearby populations, and emphasizes the need for risk reduction measures with specific guidelines to improve health and safety in aquatic facilities.

Keywords: Legionella pneumophila; aquatic therapy centre; outbreak; sequence typing.

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Conflict of interest statement

The authors declare that they have no conflict of interest.

Figures

Figure 1
Figure 1
Outbreak of Legionnaires’ disease in a district in the city of Montpellier, December 2016 to July 2017 (n = 18). Potential exposures and dates of illness were obtained from patient interviews and microbiological analyses performed by NRC-L.
Figure 2
Figure 2
(A) Minimum spanning tree of 170 Legionella pneumophila Sequence Type isolated in 2017 based SBT allelic profiles (7 genes). Blue charts represent environmental isolates from the aquatic centre; red charts represent the isolates from the patients; green charts represent the other French isolates typed in 2017. Numbers beside each circle represent the sequence type (ST). (B) Minimum spanning tree of 19 Legionella pneumophila isolates from the epidemiological investigations based on cgMLST allelic profiles (1973 genes) extracted from whole genome assemblies using chewBBACA software.
See this image and copyright information in PMC

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