Immunoenzymatic assay for the diagnosis of American tegumentary leishmaniasis using soluble and membrane-enriched fractions from infectious Leishmania (Viannia) braziliensis.

The diagnosis of American tegumentary leishmaniasis (ATL) is based on the visualization or isolation of the parasite, which is a time-consuming and poorly sensitive method. In this study, we evaluated the accuracy and reliability of ELISA for the diagnosis of ATL using soluble (SF) and membrane-enriched (MF) antigen fractions obtained from an infectious strain of Leishmania (Viannia) braziliensis. A total of 152 serum samples investigated at a referral center in Rio de Janeiro, Brazil, between 2005 and 2007 were studied. Each sample was tested twice with each fraction for the calculation of reliability (intraclass coefficient (ICC)). Cut-off values of 0.22 (SF) and 0.33 (MF) were defined. The use of the fractions resulted in good discrimination between patients, with a large area under the curve (P<0.0001), but no difference was observed between the two fractions (P=0.45). Sensitivity was 89.5% for each fraction, specificity was 89.5% for SF and 93.4% for MF, and the positive likelihood ratio was 8.5 for SF and 13.6 for MF. The ICCs were excellent (SF: 0.96 and MF: 0.90). The antigens tested provided precision and accuracy for the diagnosis of ATL, with SF being recommended due to its lower cost and greater practicality.