Human Leptospirosis on Reunion Island, Indian Ocean: Are Rodents the (Only) Ones to Blame?
Although leptospirosis is a zoonosis of major concern on tropical islands, the molecular epidemiology of the disease aiming at linking human cases to specific animal reservoirs has been rarely explored within these peculiar ecosystems.



Five species of wild small mammals (n = 995) as well as domestic animals (n = 101) were screened for Leptospira infection on Reunion Island; positive samples were subsequently genotyped and compared to Leptospira from clinical cases diagnosed in 2012-2013 (n = 66), using MLST analysis. We identified two pathogenic species in human cases, namely Leptospira interrogans and Leptospira borgpetersenii. Leptospira interrogans was by far dominant both in clinical samples (96.6%) and in infected animal samples (95.8%), with Rattus spp and dogs being its exclusive carriers. The genetic diversity within L. interrogans was apparently limited to two sequence types (STs): ST02, identified among most clinical samples and in all rats with complete MLST, and ST34, identified in six humans, but not in rats. Noteworthy, L. interrogans detected in two stray dogs partially matched with ST02 and ST34. Leptospira borgpetersenii was identified in two clinical samples only (3.4%), as well as in cows and mice; four haplotypes were identified, of which two seemingly identical in clinical and animal samples. Leptospira borgpetersenii haplotypes detected in human cases were clearly distinct from the lineage detected so far in the endemic bat species Mormopterus francoismoutoui, thus excluding a role for this volant mammal in the local human epidemiology of the disease.



Our data confirm rats as a major reservoir of Leptospira on Reunion Island, but also pinpoint a possible role of dogs, cows and mice in the local epidemiology of human leptospirosis. This study shows that a comprehensive molecular characterization of pathogenic Leptospira in both clinical and animal samples helps to gaining insight into leptospirosis epidemiology within a specific environmental setting.
Centre de Recherche et de Veille sur les maladies émergentes dans l'Océan Indien (CRVOI), Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.
Vanina
V
Guernier
Centre de Recherche et de Veille sur les maladies émergentes dans l'Océan Indien (CRVOI), Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.|Université de La Réunion, UMR PIMIT "Processus Infectieux en Milieu Insulaire Tropical", INSERM U1187, CNRS 9192, IRD 249. Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.
Erwan
E
Lagadec
Centre de Recherche et de Veille sur les maladies émergentes dans l'Océan Indien (CRVOI), Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.|Université de La Réunion, UMR PIMIT "Processus Infectieux en Milieu Insulaire Tropical", INSERM U1187, CNRS 9192, IRD 249. Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.
Colette
C
Cordonin
Centre de Recherche et de Veille sur les maladies émergentes dans l'Océan Indien (CRVOI), Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.|Université de La Réunion, UMR PIMIT "Processus Infectieux en Milieu Insulaire Tropical", INSERM U1187, CNRS 9192, IRD 249. Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.
Gildas
G
Le Minter
Centre de Recherche et de Veille sur les maladies émergentes dans l'Océan Indien (CRVOI), Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.|Université de La Réunion, UMR PIMIT "Processus Infectieux en Milieu Insulaire Tropical", INSERM U1187, CNRS 9192, IRD 249. Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.
Yann
Y
Gomard
Regional Office (Cire) of the French Institute for Public Health Surveillance (Institut de veille sanitaire), Reunion Island, France.
Frédéric
F
Pagès
Laboratory of Virology, Centre Hospitalier Universitaire/CHD, Saint-Denis, Reunion Island, France.
Marie-Christine
MC
Jaffar-Bandjee
Laboratory of Biology, Centre Hospitalier Universitaire/GHSR, Saint-Pierre, Reunion Island, France.
Alain
A
Michault
Centre de Recherche et de Veille sur les maladies émergentes dans l'Océan Indien (CRVOI), Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.|Université de La Réunion, UMR PIMIT "Processus Infectieux en Milieu Insulaire Tropical", INSERM U1187, CNRS 9192, IRD 249. Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.
Pablo
P
Tortosa
Centre de Recherche et de Veille sur les maladies émergentes dans l'Océan Indien (CRVOI), Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.|Université de La Réunion, UMR PIMIT "Processus Infectieux en Milieu Insulaire Tropical", INSERM U1187, CNRS 9192, IRD 249. Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.
Koussay
K
Dellagi
D000818:Animals; D002417:Cattle; D002685:Chiroptera; D004196:Disease Outbreaks; D004197:Disease Reservoirs / Q000662:veterinary*; D004285:Dogs; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D015994:Incidence; D007919:Leptospira / Q000235:genetics / Q000302:isolation & purification*; D007922:Leptospirosis / Q000453:epidemiology* / Q000635:transmission*; D015995:Prevalence; D017508:Reunion / Q000453:epidemiology; D012376:Rodent Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission*; D012377:Rodentia; D015047:Zoonoses