Predicting the Presence of Leptospires in Rodents from Environmental Indicators Opens Up Opportunities for Environmental Monitoring of Human Leptospirosis

• Published in: Remote Sensing
• Main Authors: Biscornet, Leon, Révillion, Christophe, Jégo, Sylvaine, Lagadec, Erwan, Gomard, Yann, Le Minter, Gildas, Rocamora, Gérard, Guernier-Cambert, Vanina, Mélade, Julien, Dellagi, Koussay, Tortosa, Pablo, Herbreteau, Vincent
• Other Authors: Processus Infectieux en Milieu Insulaire Tropical (PIMIT), Université de La Réunion (UR)-Institut National de la Santé et de la Recherche Médicale (INSERM)-IRD-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche et de Veille sur les Maladies Émergentes dans l'Océan Indien (CRVOI), Université de La Réunion (UR), Ministry of Health, Public Health Department, Victoria, Seychelles, UMR 228 Espace-Dev, Espace pour le développement, Institut de Recherche pour le Développement (IRD)-Université de Perpignan Via Domitia (UPVD)-Avignon Université (AU)-Université de La Réunion (UR)-Université de Montpellier (UM)-Université de Guyane (UG)-Université des Antilles (UA), University of Seychelles
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: leptospirosis; rodents; Rattus rattus; Rattus norvegicus; spatial analysis; remote sensing; landscape metrics; satellite; ecology; [SDV.MHEP.MI]Life Sciences [q-bio]/Human health and pathology/Infectious diseases; Main Island
• Online Access: https://hal.univ-reunion.fr/hal-03129657; https://hal.univ-reunion.fr/hal-03129657/document; https://hal.univ-reunion.fr/hal-03129657/file/remotesensing-13-00325.pdf; https://doi.org/10.3390/rs13020325

International audience Leptospirosis, an environmental infectious disease of bacterial origin, is the infectious disease with the highest associated mortality in Seychelles. In small island territories, the occurrence of the disease is spatially heterogeneous and a better understanding of the environmental factors that contribute to the presence of the bacteria would help implement targeted control. The present study aimed at identifying the main environmental parameters correlated with animal reservoirs distribution and Leptospira infection in order to delineate habitats with highest prevalence. We used a previously published dataset produced from a large collection of rodents trapped during the dry and wet seasons in most habitats of Mahé, the main island of Seychelles. A land use/land cover analysis was realized in order to describe the various environments using SPOT-5 images by remote sensing (object-based image analysis). At each sampling site, landscape indices were calculated and combined with other geographical parameters together with rainfall records to be used in a multivariate statistical analysis. Several environmental factors were found to be associated with the carriage of leptospires in Rattus rattus and Rattus norvegicus, namely low elevations, fragmented landscapes, the proximity of urbanized areas, an increased distance from forests and, above all, increased precipitation in the three months preceding trapping. The analysis indicated that Leptospira renal carriage could be predicted using the species identification and a description of landscape fragmentation and rainfall, with infection prevalence being positively correlated with these two environmental variables. This model may help decision makers in implementing policies affecting urban landscapes and/or in balancing conservation efforts when designing pest control strategies that should also aim at reducing human contact with Leptospira-laden rats while limiting their impact on the autochthonous fauna.