Comparison between ELISA using total antigen and immunochromatography with antigen rK39 in the diagnosis of canine visceral leishmaniasis

In this study, an enzyme-linked immunosorbent assay using crude total antigen (CTA-ELISA) and immunochromatography with antigen rK39 were compared in the diagnosis of canine visceral leishmaniasis (CVL). Fifty-two total blood samples from symptomatic dogs obtained from a location endemic for leishmaniasis and 52 blood samples from healthy dogs from a nonendemic region were tested. Polymerase chain reaction (PCR) was used to detect DNA from Leishmania spp. in both groups. Symptomatic dogs with positive PCR were considered infected by Leishmania spp. and the PCR technique was chosen as a gold standard test. The sensitivity determined for CTA-ELISA was 100%, with specificity of 91.2%, while the immunochromatographic assay with the antigen rK39 showed sensitivity of 91.5%, with specificity of 94.7%. A strong correlation was verified between CTA-ELISA and immunochromatography with antigen rK39, with a kappa coefficient of agreement of 0.88. Analysis of the results suggested that both assays presented good sensitivity and specificity for diagnosing CVL; however, immunochromatography with the antigen rK39 may be more advantageous when a fast field test is required.