Seeking the environmental source of Leptospirosis reveals durable bacterial viability in river soils.

International audienceBACKGROUND:Leptospirosis is an important re-emerging infectious disease that affects humans worldwide. Infection occurs from indirect environment-mediated exposure to pathogenic leptospires through contaminated watered environments. The ability of pathogenic leptospires to persist in the aqueous environment is a key factor in transmission to new hosts. Hence, an effort was made to detect pathogenic leptospires in complex environmental samples, to genotype positive samples and to assess leptospiral viability over time.METHODOLOGY/PRINCIPAL FINDINGS:We focused our study on human leptospirosis cases infected with the New Caledonian Leptospira interrogans serovar Pyrogenes. Epidemiologically related to freshwater contaminations, this strain is responsible for ca. 25% of human cases in New Caledonia. We screened soil and water samples retrieved from suspected environmental infection sites for the pathogen-specific leptospiral gene lipL-32. Soil samples from all suspected infection sites tested showed detectable levels of pathogenic leptospiral DNA. More importantly, we demonstrated by viability qPCR that those pathogenic leptospires were viable and persisted in infection sites for several weeks after the index contamination event. Further, molecular phylogenetic analyses of the leptospiral lfb-1 gene successfully linked the identity of environmental Leptospira to the corresponding human-infecting strain.CONCLUSIONS/SIGNIFICANCE:Altogether, this study illustrates the potential of quantitative viability-PCR assay for the rapid detection of viable leptospires in environmental samples, which might open avenues to strategies aimed at assessing environmental risk

Assurpluhyt (volet 1) : aspects sanitaires des eaux de surface : une approche pluridisciplinaire de la contamination hydrique par la leptospirose sur un site pilote à Touho

Workshop "Au fil de l'eau", Nouméa, NCL, 17-/09/2019 - 18/09/201

Seasonal shifts in the presence of pathogenic leptospires, Escherichia coli

Leptospirosis is an emerging zoonotic disease in the Caribbean region and the island of Puerto Rico. Information on the presence of pathogenic Leptospira in rivers and streams of Puerto Rico is currently lacking. This study aimed to evaluate seasonal shifts in the presence of pathogenic leptospires and the level of Escherichia coli from 32 coastal locations in Puerto Rico\u27s dry and wet seasons. Physicochemical parameters (temperature, salinity, pH, and dissolved oxygen) were determined at each site. The temperature (25.8 °C) and pH (average 7.6) values were all within acceptable USEPA regulatory standards. Thirty-eight percent of the sites of the dry season and 28% of the wet season sites contained dissolved oxygen levels ≤4 mg L−1, which is relatively low. In the dry season, 19 sites (59%) and 18 (56%) of the wet season sites had E. coli counts \u27410 most probable number (MPN) 100 ml−1 and would be considered unsafe for recreational use. The lipl32 gene quantitative polymerase chain reaction assay was used for the detection of pathogenic leptospires in the samples. Low concentrations of pathogenic leptospires (\u2760 genome copies 100 ml−1) at Camuy, Espíritu Santo, Río Guayanilla, Quebrada Majagual, and Río Fajardo were detected during the wet season. Pathogenic leptospires were detected (∼40 genome copies 100 ml−1) at only one site, Loíza, during the dry season. There was no predictable relationship between the physicochemical parameters, concentrations of E. coli, and the presence of pathogenic leptospires in water samples