A 2-mercaptoethanol-ELISA for the diagnosis of canine visceral leishmaniasis.

Following procedures of antigen preparation similar to those described for the direct agglutination test (DAT), an IgG ELISA employing promastigotes of Leishmania infantum was developed for the diagnosis of canine visceral leishmaniasis (CVL). The newly developed β-ME-ELISA was also compared with an ELISA version using instead of β-ME-treated, trypsin-treated promastigote (TRYP-ELISA) antigen. While in comparison with DAT (31/31 = 100%) slightly lower sensitivity (29/31 = 93.5%) was demonstrated for the β-ME-ELISA developed in dogs with confirmed CVL, evidently higher sensitivity was estimated in the same canine population by comparison with the TRYP-ELISA (27/31 = 87.1%). When challenged against conditions other than CVL: including babesiosis, ehrlichiosis and Chagas’s disease, a specificity of 97.5% was estimated for β-ME-ELISA as compared to 100% or 94.1% for DAT and TRYP-ELISA respectively. In an endemic population manifesting CVL clinical suspicion (n=38), results obtained with the β-ME ELISA were more concordant (33/38 = 86.3%) with those of the DAT than the TRYP-ELISA (27/38 = 71.1%). In this group of unconfirmed CVL, the incorporated β-ME treated promastigote antigen has demonstrated also higher sensitivity (29/31 = 93.5% or 62/69 = 88.9%) in comparison with that of its trypsinized equivalent (27/31 = 87.1% or 54/69 = 78.2%). Our current results implicate the application of β-ME ELISA in the laboratory to support results obtained in the field with the DAT