Molecular and Epidemiological Surveillance of Sporothrix spp. in Cats and Dogs from Southern Brazil.

Sporotrichosis, a subcutaneous mycosis caused by Sporothrix spp., has emerged as a major zoonotic disease in Brazil, primarily driven by Sporothrix brasiliensis. The southern state of Rio Grande do Sul exhibits distinctive ecological and climatic conditions that may shape the persistence and distribution of this pathogen in this region. This study conducted molecular and epidemiological surveillance of feline and canine sporotrichosis in southern Rio Grande do Sul, Brazil. A total of 100 isolates from the culture collection of the Veterinary Mycology Laboratory at the Federal University of Pelotas (UFPel) were analyzed by PCR targeting the calmodulin (CAL) gene for species identification. Fourteen representative isolates were sequenced and subjected to phylogenetic analysis using the Maximum Likelihood method, including reference sequences from Brazil, Paraguay, and Argentina. Epidemiological and clinical variables, including host species, sex, lesion site, and morphology, were evaluated to characterize the epidemiological and clinical profiles of sporotrichosis in the study region. S. brasiliensis and S. schenckii were identified in 97% and 3% of the isolates, respectively. The CAL-based phylogeny confirmed the monophyly of S. brasiliensis and revealed low intraspecific variability with regional clustering among southern Brazilian isolates. When interpreted within the Southern Cone context, the topology indicated a close genetic affinity between isolates from Rio Grande do Sul and reference sequences from Argentina and Paraguay. These findings confirm the territorial expansion of S. brasiliensis across southern Brazil and emphasize the importance of molecular surveillance for detecting and tracking the circulating lineages. Continuous regional monitoring is crucial for strengthening One Health strategies and mitigating the zoonotic spread of sporotrichosis in the Southern Cone.