Evaluation of real-time PCR, MAT, and recombinant LipL32-based ELISA for the diagnosis of canine leptospirosis in a disease-endemic South Indian state, Kerala

Abstract

Canine samples (n = 425) collected from cases of suspected leptospirosis over a period of 6 years were tested using themicroscopic agglutination test (MAT), recombinant LipL32-based IgM and IgG ELISA, and real-time PCR (RT PCR). A prevalence of69.41% was recorded by MAT. Among the different tests, IgG ELISA was observed to have maximum agreement with that of MAT (k0.810), followed by IgM ELISA (k-0.762.). RT PCR had only slight agreement with MAT (k-0.156). However, the percentage positivityof RT PCR with samples with MAT titers of 1:100 and 1:200 were 76.47% and 85.96%, respectively, indicating the reliability of RT PCRin the early phase of the disease. The values for the samples at higher MAT titers of 1:400 and 1:800 were 10.58% and 1.2%, respectively,clearly indicating the unreliability of the test for samples having high antibody titers. It was concluded that IgG ELISA could be usedas the routine test for the diagnosis of canine leptospirosis in this disease-endemic region. Samples with negative results that have highsymptomatic correlation with leptospirosis may be tested by PCR/RT PCR for the detection of the pathogen well ahead of antibodygeneration.