Sensitivity and specificity of an in-clinic point-of-care PCR test for the diagnosis of canine leishmaniasis

Abstract

Canine leishmaniasis is an important infectious disease worldwide. Although commonly used, antibody tests are often falsely negative, and in such cases direct detection of the pathogen, such as PCR, is necessary. However, PCR is only performed in specialized laboratories and not available in all localities. The aim of this study was to compare the sensitivity and specificity of an in-clinic point-of-care (ICPOC) PCR for the diagnosis of canine Leishmania spp. infection to those of a well characterized reference real-time PCR. In this study, 515 samples from 251 dogs (201 EDTA blood samples, 244 conjunctival swabs, 19 lymph node aspirates, and 51 bone marrow aspirates) were collected prospectively and analysed for the presence of Leishmania DNA using an ICPOC test. The results were compared to those of a reference real-time PCR for identification of Leishmania kinetoplast minicircle DNA. Sensitivity and specificity with 95% confidence interval (CI 95%) were determined.Specificity was 100% for all samples examined. Sensitivity was 57.1% (CI 95%, 34.0–78.2) in bone marrow aspirates, 58.8% (CI 95%, 32.9–81.6) in lymph node aspirates, 46.9% (CI 95%, 32.5–61.7) in conjunctival swabs, and 10.0% (CI 95%, 3.3–21.8) in blood. The ICPOC PCR was easy to perform and was reliable in the case of positive test results. A negative result, however, did not exclude infection and therefore requires further diagnostics.