title: Seeking the environmental source of Leptospirosis reveals durable bacterial viability in river soils.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: Institut Pasteur in New Caledonia, Institut Pasteur International Network, Leptospirosis Research and Expertise Unit, Noumea, New Caledonia.
authors.forename: Roman
authors.initials: R
authors.lastname: Thibeaux
authors.affiliation: Institut Pasteur in New Caledonia, Institut Pasteur International Network, Leptospirosis Research and Expertise Unit, Noumea, New Caledonia.
authors.forename: Sophie
authors.initials: S
authors.lastname: Geroult
authors.affiliation: Institut Pasteur in New Caledonia, Institut Pasteur International Network, Leptospirosis Research and Expertise Unit, Noumea, New Caledonia.
authors.forename: Claire
authors.initials: C
authors.lastname: Benezech
authors.affiliation: Health Department, Direction of Health and Social Affairs of New Caledonia, Noumea, New Caledonia.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Chabaud
authors.affiliation: Institut Pasteur in New Caledonia, Institut Pasteur International Network, Leptospirosis Research and Expertise Unit, Noumea, New Caledonia.
authors.forename: Marie-Estelle
authors.initials: ME
authors.lastname: Soupé-Gilbert
authors.affiliation: Institut Pasteur in New Caledonia, Institut Pasteur International Network, Leptospirosis Research and Expertise Unit, Noumea, New Caledonia.
authors.forename: Dominique
authors.initials: D
authors.lastname: Girault
authors.affiliation: Institut Pasteur in New Caledonia, Institut Pasteur International Network, Leptospirosis Research and Expertise Unit, Noumea, New Caledonia.
authors.forename: Emilie
authors.initials: E
authors.lastname: Bierque
authors.affiliation: Institut Pasteur in New Caledonia, Institut Pasteur International Network, Leptospirosis Research and Expertise Unit, Noumea, New Caledonia.
authors.forename: Cyrille
authors.identifier: 0000-0002-0690-9464
authors.initials: C
authors.lastname: Goarant
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D016000:Cluster Analysis; D006801:Humans; D007921:Leptospira interrogans / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology*; D007922:Leptospirosis / Q000453:epidemiology* / Q000382:microbiology*; D008074:Lipoproteins / Q000235:genetics; D050296:Microbial Viability; D017720:Molecular Epidemiology; D009510:New Caledonia / Q000453:epidemiology; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction; D045483:Rivers / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D012988:Soil Microbiology
chemical_list: D001425:Bacterial Outer Membrane Proteins; C406589:LipL32 protein, Leptospira; D008074:Lipoproteins