Molecular Epidemiology of Pathogenic Leptospira spp. Infecting Dogs in Latin America

Simple Summary Leptospirosis is a neglected zoonosis caused by a bacterium of the genus Leptospira. Dogs are highly susceptible to infection, which can range from chronic and asymptomatic to acute and severe disease. Although serosurveys of canine leptospirosis in Latin America are widely published, the gathering of molecular data of strains identified from dogs has not yet been performed. Based on Leptospira spp. DNA sequences collected on digital platforms, we aimed to genetically analyze the strains circulating in Latin America in order to provide an unprecedented overview of the molecular epidemiology of pathogenic leptospires infecting dogs in the region. We found a very high genetic similarity between strains apart serogroup, clinical signs, or geographical localization. The strains were similar to the one that most circulates in humans. In addition to the importance from a zoonotic point of view, this high genetic similarity between strains can, in theory, facilitate the development of an effective broad-spectrum vaccine across the continent, as well as enable the standardization of rapid diagnostic tests. Canine leptospirosis is a bacterial disease caused by spirochetes of the genus Leptospira. Infections can vary from asymptomatic and chronic infections to clinical acute diseases. The disease is endemic in tropical areas, such as Latin American countries, but a broad understanding of the dynamics of circulation of strains, based on molecular data, has not yet been performed. Based on in silico analyses, the present study aims to analyze the genetic diversity and circulation patterns of haplotypes from pathogenic leptospires infecting dogs in Latin America. DNA sequences were obtained from GenBank platform, curated, and aligned. Genetic distances were calculated, and a maximum likelihood tree and haplotype network were constructed. According to the inclusion criteria adopted, a total of 148 sequences were identified. Most of the records were from Brazil, including sequences from L. interrogans serogroup Icterohaemorrhagiae. Phylogenetic analysis showed a genetically closely related cluster, consisting of a larger haplogroup that includes the reference strain Fiocruz L1-130, known to be the major circulating strain in humans. Moreover, no genetic variations were observed according to clinical history and/or geographical localization. We described the molecular epidemiology of leptospires circulating among dogs in Latin America and demonstrated a very genetically homogeneous group, elucidating its ubiquitous circulation pattern and drawing attention to the important role of dogs in the One Health transmission dynamics of leptospirosis.

Automated summary

This study analyzed the genetic sequences of Leptospira strains from dogs in Latin America and found a high genetic similarity between the strains, as well as similarity to those that infect humans. This has important implications for vaccine development and standardization of diagnostic tests.