Isolation, Molecular Detection, and Sequence Analysis of Pathogenic <i>Leptospira</i> spp. in Paddy Field Water Samples in Amol, Northern Iran

Background: Leptospirosis constitutes a zoonotic affliction prevalent in tropical and subtropical locales, instigated by the pathogenic strains of Leptospira. The objective of the present study was to isolate and detect Leptospira from water samples sourced from paddy fields located in Amol, northern Iran. Methods: A total of 108 samples were procured from rice fields during the spring and summer of 2023. Cultivation, microscopy, and molecular analyses were employed to accurately identify L. interrogans. Both conventional and real-time polymerase chain reactions (RT-PCR) targeting the lipL32 gene were executed for the detection of L. interrogans. In addition, the sequence analysis of the sucA and gluM genes was performed after PCR. Results: The findings revealed that 6/108 (5.55%) of the samples were culture-positive, with all cases corroborated through both RT-PCR and traditional PCR methods. A simple PCR assay showed positive results for 17/108 (15.74%) water samples. RT-PCR successfully identified 17/108 (15.74%) samples as positive for L. interrogans. The sequence analysis of the sucA gene from the water sample demonstrated high similarity to Leptospira weilii. Eventually, the sequence analysis of the gluM gene from two water samples displayed high similarity to Leptospira borgpetersenii. Conclusion: This investigation highlights the efficacy of synergizing molecular techniques with traditional culture methodologies for the surveillance of Leptospira in areas characterized by an elevated risk. The current research serves as the inaugural report, delineating the emergence of leptospires from rice field samples, alongside the characterization of isolates obtained from culture.