Genetic Characterization and Zoonotic Potential of Leptospira interrogans Identified in Small Non-Flying Mammals from Southeastern Atlantic Forest, Brazil.

Leptospirosis is a zoonotic disease of global public health importance caused by bacteria of the genus Leptospira. Small non-flying mammals are important reservoirs of the pathogen. The Brazilian Atlantic Forest is a biodiversity hotspot located in a densely populated area and subject to intense degradation. Although documented through serosurveys and the detection of leptospiral DNA in wild small mammals, no study has performed a genetic characterization of the bacteria in the region. The present study aimed to evaluate the genetic diversity of pathogenic leptospires identified in small non-flying mammals in the Southeast Atlantic Forest and to perform intraspecific genetic inferences with other hosts. The studied area included five different conservation units. Molecular diagnosis was performed based on the lipl32 gene. The SLST typing method was applied based on the secY gene. In total, 56% of samples were lipL32-PCR-positive and identified as L. interrogans, with a high genetic identity among them, distributed in four main haplogroups. The largest haplogroup also included reference sequences from humans, dogs, and urban rats, all belonging to the Icterohaemorrhagiae serogroup. Our results reinforce the role of small mammals as important carriers of L. interrogans and highlight the Atlantic Forest as a significant environment for the circulation and dissemination of spirochetes with zoonotic potential.