Molecular and serological detection of acute canine leptospirosis and associated predictive risk factors in and around Chennai, India.

Leptospirosis is a globally important re-emerging zoonotic disease affecting humans and many animal species including dogs. The present cross-sectional study aimed to diagnose acute leptospirosis among 210 suspected dogs using microscopic agglutination test (MAT) and polymerase chain reaction (PCR). Further, epidemiological risk factors were analyzed by univariate analysis and multivariate binomial logistic regression analysis. Out of the 210 dogs, anti-leptospiral antibody was detected in 123 (58.57 %; 95 % CI: 51.6-65.3) dogs by MAT (cut-off titer- ≥1:100), among which 67 (54.47 %; 95 % CI: 45.3-63.4) were seropositive to more than one serogroup. The predominant serogroups were Australis and Autumnalis in the study region. Whereas, acute leptospirosis was established in 49 (23.33 %, 95 % CI: 17.9-29.8) dogs based on ≥ 1:800 titer in unvaccinated dogs and ≥1:1600 titer in vaccinated dogs. The predictive risk factors of acute canine leptospirosis were adult dogs (1-5 years) (p = 0.001), north-east monsoon season (p = 0.011), outdoor management (p = 0.047), history of rodent exposure (p = 0.001) and history of contact with wet soil or stagnant water (p = 0.046). Among 49 acutely infected dogs, thirteen dogs were positive for urine PCR and one dog was positive for both urine as well as plasma PCR. Positive PCR amplicons were identified as Leptospira interrogans based on secY gene sequencing and phylogenetic analysis. This study enlightened about the occurrence of acute leptospirosis among suspected dogs with the above important predictive risk factors, which should be taken into consideration while history taking so that proper treatment strategies can be adopted for early recovery of the animal.