A comparative evaluation of rapid immunochromatographic test for VL - whole blood vs serum

Abstract

Background: Diagnosis of leishmaniasis is still a challenge in front of investigator. A firm diagnosis of visceral leishmaniasis (kala azar) requires demonstration of the parasite in organ aspirates or tissue biopsy samples. The aim of this prospective study was to assess the diagnostic usefulness of non-invasive testing for antibody to the leishmanial antigen by means of antigen-impregnated nitrocellulose paper strips adapted for use under field as well as laboratory conditions. There are so many rapid diagnostic tests (RDTs) of different brands available and published report of variable accuracy. Methods & Materials: This study of evaluation includes six commercially available VL-RDTs of four different manufacturers. These VL-RDTs were evaluated using whole blood as well as serum at two different conditions (At bed site and laboratory site). In this study total 135 confirmed VL cases, 85 endemic healthy with no kala azar history, 15 malaria patients and 20 tuberculosis patients were enrolled. The interpretation was recorded into a data sheet. Results: Overall, our finding illustrates that different RDTs demonstrated varied sensitivity and specificity. At field site the sensitivity with whole blood is ranges from 96.3% to 100% while with serum ranges from 96.3% to 99.3%. Specificity with whole blood ranges from 97.4% to 100%. Specificity with serum ranges from 94.1% to 100% except onsite RevB of CTK biotech which has lower specificity. Agreements of test result at field site with whole blood and serum is ranges from 0.44-0.98. At lab site the sensitivity with whole blood ranges from 94.8% to 100%. Specificity with whole blood ranges from 95.8% to 99.2% except onsite Rev B which has 52.9% specificity. While with serum the sensitivity of all the test ranges from 97% to 99.3%. Specificity with serum ranges from 92.4% to 98.3% except onsite Rev B has only 50.4% specificity. Agreements of test result between whole blood and serum at lab site ranges from 0.46 – 0.97 Conclusion: Diagnostic accuracy of different VL RDTs kits are varies. Many test performed good sensitivity and specificity against blood and serum sample as well as field site and lab site.