Molecular Detection and Genotyping of Pathogenic Leptospira in Small Mammals from Southern Vietnam

Leptospirosis is a major zoonosis, yet genetic data on <i>Leptospira</i> strains in animal reservoirs in Southern Vietnam are limited. This study aimed to detect and genotype pathogenic <i>Leptospira</i> in synanthropic small mammals. From 2016 to 2020, 856 animals were captured in three regions. Kidneys were screened by qPCR targeting pathogenic <i>Leptospira</i> 16S rRNA, and positive samples were genotyped via <i>secY</i> gene sequencing. The overall prevalence was 7.8%. <i>Rattus norvegicus</i> was the primary host (12.4% infected). <i>Leptospira interrogans</i> predominated (77.6%), followed by <i>L. borgpetersenii</i> (22.4%). Infection risk was significantly associated with the following factors: larger host body size (increased body mass and hindfoot length); capture in Ho Chi Minh City; and the rainy season. The study confirms the stable circulation of highly virulent <i>L. interrogans</i> in urban <i>R. norvegicus</i> populations. The identified risk factors provide a basis for targeted interventions to mitigate human health risks.