Co-occurrence of leptospirosis and Opisthorchis viverrini infection in cats and their risk factors.

Leptospirosis is a waterborne disease with a worldwide distribution. In Northeast Thailand, its prevalence overlaps with the endemicity of Opisthorchis viverrini, (OV). This study aimed to investigate the prevalence and risk factors of leptospirosis in cats and its association with opisthorchiasis in endemic area of Thailand. 115 cats were sampled for blood and feces. We tested Leptospira antibodies in blood using the Lepto-latex test. For fecal analysis, we applied the formalin-ether concentration technique (FECT) for OV and identified Leptospira spp. through PCR targeting the 16S rRNA and LipL32. Non-spatial analyses included Pearson's Chi-square, Fisher's exact test, and logistic regression, while spatial analyses involved Inverse Distance Weighted (IDW), spatial autocorrelation, and Geographically Weighted Logistic Regression (GWLR). Serological analysis revealed 15.65 % of cats positive for Leptospira spp., whereas 44.35 % of fecal samples positive for OV. PCR analysis identified 1 L. interrogans with the 16S rRNA, while the LipL32 identified 2 samples related to L. interrogans and 1 to L. borgpetersenii. The spatial autocorrelation indicated clustering of leptospirosis cases. Logistic regression revealed 2 significant risk factors; OV infection (OR 3.44, 95 % CI 1.10-10.73; p 0.03) and proximity to flooded areas (OR 3.47, 95 % CI 1.12-10.74; p 0.03). Furthermore, GWLR showed median coefficients of 0.59 (-1.62-5.15) for OV infection and 2.15 (1.30-6.47) for proximity to flooded areas. This study demonstrates a significant association between cat leptospirosis with OV infection and proximity to flooded areas. These highlight the importance of monitoring environmental and biological risk factors to mitigate leptospirosis in endemic regions.