First Observation of Leptospira interrogans in the Lungs of Rattus norvegicus

We report the first two cases of pulmonary presence of leptospires in apparently healthy rats captured in a city park in Lyon (France). Only renal carriage ofLeptospirahas been described in the literature. Blood serology was performed in parallel with molecular and histological analyses of the kidney and lung samples. We isolated leptospires from the kidneys of two out of three seropositive wild rats. These results were confirmed by specific detection of pathogenicLeptospiraby real-time PCR. Moreover,LeptospiraDNA was detected in lung tissues. Immunohistochemistry and Warthin-Starry staining revealed that leptospires were present on the surface of the ciliated epithelium of the bronchi. Using PCR of therrs(16S) gene and Multispacer Sequence Typing, DNA extracts of the kidney and lung were identified as belonging toLeptospira interrogansserovar Icterohaemorrhagiae “CHU Réunion.” This first observation of the presenceLeptospirain the lung with simultaneous renal carriage will require further study in future on several target organs to gain a better understanding of theLeptospirainfection in wild rat.