Evolutionary insights into the geographic spread of pathogenic and opportunistic Leptospira strains

Leptospirosis, a global health concern caused by Leptospira sp. is largely unknown due to its elusive phylogeographic distribution and flow. Therefore, this study aimed to understand the geographical distribution and evolutionary changes of pathogenic, non-pathogenic, and opportunistic strains of Leptospira. This study used genome-scale data, 16S rDNA gene sequences, and virulence proteins to construct precise phylogenetic trees using robust bootstrapping techniques. Phylogenomic studies indicated that pathogenic Leptospira strains constituted a distinct cluster from opportunistic and non-pathogenic variants. The pathogenic strains coalesced, creating a central group in the phylogenetic tree based on the 16S rDNA gene. Pathogenic strains had a close evolutionary relationship with non-pathogenic and opportunistic strains, since they shared the outer membrane protein L. The opportunistic strains formed a clearly defined clade, suggesting that there were no evolutionary transitions between them. Nevertheless, we found potential transitions between the pathogenic and non-pathogenic strains. Additionally, this study unveiled the participation of prominent countries in the dissemination of Leptospira strains to various geographical areas, such as Thailand, the USA, Peru, Italy, Turkey, Malaysia, New Caledonia, Brazil, and Iran. This work provides novel perspectives on the evolutionary shift, geographical dissemination, and emergence of highly pathogenic Leptospira strains.