Tracking potential sources following human cases of leptospirosis: A One Health approach applied to an ecosystem in Brittany, France.

Pathogenic can cause leptospirosis: a widespread, potentially fatal bacterial zoonosis whose risk is mediated by the soil and water features, animal host distributions, meaning the local ecosystem. When human cases of leptospirosis occur, it is challenging to track down their source because ecosystem-level epidemiological knowledge on is needed. Between 2016 and 2019 in a focal riparian ecosystem, the human population experienced an outbreak and successive cases of leptospirosis attributable to L. and L. . The epidemiological investigation was carried out using the One Health approach, as described in international health guidelines. As a first step in this process, we investigated leptospiral carriage in the main animal hosts found in the region. We sampled 143 nutrias, 17 muskrats, and 10 Norway rats using convenient trapping. DNA was extracted from their kidneys, lungs, and urine and subjected to real-time PCR (RT-PCR) targeting the 16S rDNA and genes. In the farms along the river's stretch of interest, we sampled serum from 439 cattle and used a microscopic agglutination test to detect the presence of antibodies against . Urine samples were concomitantly obtained from 145 cattle and were used in two analyses: RT-PCR targeting the 16S rDNA gene and culturing. We found th, wt rodents were the most likely source of the L. behind the human cases. The cattle tested negative for DNA but positive for antibodies against the serogroups implicated in the human cases. We failed to identify the potential source of the L. responsible for several human cases of leptospirosis. Our results call for further clarification of the maintenance community, which may comprise known maintenance hosts, such as rodents, as well as taxa not commonly considered to be maintenance hosts but that can still spread . The resulting research network will collaboratively conduct future eco-epidemiological surveys to illuminate the leptospirosis risks faced by humans and animals within ecosystems.