Accuracy of an ELISA and indirect immunofluorescence for the laboratory diagnosis of American tegumentary leishmaniasis.

ABSTRACT

We compared the accuracy of ELISA and indirect immunofluorescence (IIF) using Leishmania braziliensis and L. major-like antigens and antigens from the Bio-Manguinhos kit for serological diagnosis of American tegumentary leishmaniasis (ATL). Cut-off values were defined by the area under the receiver-operating characteristic curve. For ELISA, statistical analyses revealed better accuracy [95.7% sensitivity, 100% specificity, 100% positive predictive value (PPV), 97.5% negative predictive value (NPV)] and reliability [intraclass correlation coefficient (ICC) 0.940] for L. braziliensis antigen compared with L. major-like antigen (78.7% sensitivity, 82.8% specificity, 73.3% PPV, 86.6% NPV, ICC 0.833). ELISA optical density values obtained for both antigens were higher in mucosal forms of ATL. For IIF, sensitivity and specificity were 81.5 and 86.2%, respectively, for the L. braziliensis antigen, compared with 95.4 and 77.7% for the L. major-like antigen and 75.4 and 89.2% for the Bio-Manguinhos kit. No difference in the specificity of the IIF test was observed between antigens, whereas sensitivity differed between the L. braziliensis and L. major-like antigens and the Bio-Manguinhos kit. Parallel ELISA and IIF testing increased sensitivity, irrespective of the antigen employed, and serial testing increased overall specificity. These results support the recommendation that ELISA employing L. braziliensis antigen be used as a diagnostic tool for suspected cases of ATL in L. braziliensis-endemic areas.