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Étude des leptospires dans les eaux de surface à Paris : quantification, dynamique, persistance et identification des espèces circulantes

Abstract : Pathogenic Leptospira are responsible for a worldwide zoonosis, leptospirosis, where humans can be an occasional host whose infection involves both wild and domestic animals. The animal reservoir, mainly rodents that are asymptomatics, excrete Leptospira through urine and contaminate surface water. Since 2015, nearly 600 cases of leptospirosis have been identified in Metropolitan France area. The increase in the number of cases could be due to several factors, including the increase in risky behavior (eg: water sports). The study of Leptospira ecology in aquatic environments has been developed in recent years, but these bacteria are still not included in the water sanitary monitoring. Water activities in densly populated urban areas are increasingly used and could increase users' exposure to pathogens, including leptospira.In this work we have tried to obtain a first glance of the Leptospira presence in Parisian surface waters. An integrity multiplex qPCR has been developed to this purpose. Based on two specific genes and tested in several bacterial inactivation tests (UV, chlorination, etc.), it allows the detection of all Leptospira (rrs gene) but also the distinction of pathogens (lipL32 gene). From June 2018 to September 2020, this method was applied to the investigation of pathogenic Leptospira in rats (more than 190 kidneys analyzed) and on several surface water sites (more than 1000 samples), predisposed to accommodate swimming areas. Secondly, a diversity comparison of strains circulating in water and those identified in rats (potential main reservoir) had also been studied by NGS sequencing. Analysis of rat kidneys revealed the classification of a single OTU, grouping together with pathogenic species. Due to the great diversity of Leptospira and bacteria in surface waters, the diversity within environmental samples is more important but could sometimes include pathogenic Leptospira. Pathogenics strains seem to decrease in the recent years.For the first time, these results make it possible to know the environmental contamination in the bathing areas, using Paris as a "pilot" region in the context of the programmed opening of bathing areas in surface water. As part of the One Health approach, this project aims to help the medical community, the population and the water health control services to know the potential risk associated with these bacteria; and if justified, to put in place preventive measures.
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  • HAL Id : tel-03541692, version 1

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Élise Richard. Étude des leptospires dans les eaux de surface à Paris : quantification, dynamique, persistance et identification des espèces circulantes. Ingénierie de l'environnement. École des Ponts ParisTech, 2021. Français. ⟨NNT : 2021ENPC0014⟩. ⟨tel-03541692⟩

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