Antigen detection ELISA: A sensitive and reliable tool for the detection of active infection of surra.

Trypanosomosis, an endemic disease in Asia, America (central and south) and Africa causes havoc economical loss in livestock industry. The carrier animals which are symptomless and harbours low level of parasites can act as a source of infection. The level of parasitaemia fluctuates, especially during the latent infection; moreover the antibodies which are not found early in the infection may persit even after recovery or chemotherapy. The parasitological and/or serological tests always can not detect current infection or carrier animals. Hence, in the present study double antibody sandwitch antigen detection ELISA (Ag-ELISA) is developed to detect circulating trypanosomes. The new assay has been evaluated using 554 field samples comprising bovine and camel. The diagnostic sensitivity and specificity of the new assay was found to be 97.4% and 99.0% respectively, with a Cohen's kappa value of 0.96. The developed assay could detect 11.5 Trypanosoma evansi per mL from the experimentally infected blood, buffy coat and purified T. evansi samples. The findings revealed that the developed assay can be exploited as a potential diagnostic tool in the detection of active trypanosomal infection.