Molecular detection of Leptospira spp. in urinary and vaginal samples of domestic and free-roaming cats in Tehran, Iran.

Objective

Leptospirosis is a globally important zoonotic disease associated with renal and hepatic injury. Cats are frequently exposed to Leptospira spp., yet their epidemiological role remains unclear. This study aimed to determine whether Leptospira DNA could be detected in feline vaginal samples, in addition to urine, using Nested-PCR. Secondary objectives were to determine the proportion of PCR-positive cats and assess renal involvement by comparing renal parameters between PCR-positive and PCR-negative cats.

Methods

Seventy-six domestic and free-roaming cats were examined in Tehran, in 2025. Urine samples were collected from all cats and vaginal swabs from female cats. Nested-PCR targeting the 16S rRNA (rrs) gene was performed on both sample types followed by confirmatory sequencing of representative amplicons. Renal status was assessed using biochemical, hematological, and urinalysis parameters in all cats.

Results

Leptospira DNA was detected in 15/76 cats (19.7%). Positive results were obtained from urine samples in 10/76 cats (13.1%) and from vaginal swabs in 5/61 female cats (8.2%), with no concordant positive results between urine and vaginal samples (95% CIs reported). Vaginal PCR identified Leptospira DNA in cats that were negative by urine PCR. No significant differences were observed in biochemical, hematological or urinalysis parameters between PCR-positive and PCR-negative cats.

Conclusions

Leptospira DNA was detected in urine and vaginal samples of both domestic and free-roaming cats, frequently in subclinical animals without observable clinical signs. The absence of concordance between urine and vaginal PCR results suggests that vaginal sampling may provide complementary molecular detection to urine testing. Further investigation is warranted to elucidate the biological significance and clinical implications of Leptospira DNA detection in feline vaginal samples.