Studies on the control of visceral leishmaniasis: validation of the Falcon assay screening test--enzyme-linked immunosorbent assay (FAST-ELISA) for field diagnosis of canine visceral leishmaniasis.

TLDR: The FAST-ELISA system provides a sensitive, specific, and field-adaptable test for canine visceral leishmaniasis, which can be evaluated quickly without the use of a microscope or spectrophotometric results.

Abstract: The Falcon assay screening test-enzyme-linked immunosorbent assay (FAST-ELISA), the latest version of the enzyme-linked immunosorbent assay, uses antigen-coated beads. A 96-well plate can be run in 20 min without electricity or expensive equipment. We compared the FAST-ELISA, a standard ELISA, and an indirect immunofluorescent assay (IFA) for evaluation of canine leishmaniasis under field conditions using samples from 161 dogs from our longitudinal study in the endemic area of Jacobina, Bahia, Brazil. Organisms were isolated by culture (NN medium) or by inoculation of hamsters with samples from 59 of the dogs. When plasma were tested, we found a sensitivity of 88% and a specificity of 90% using the FAST-ELISA with a spectrophotometer. Using the same plasma samples, the IFA had a sensitivity of 75% and a specificity of 93%. The standard ELISA had a sensitivity of 90% and a specificity of 85%. When whole blood was tested with the FAST-ELISA, we found a sensitivity of 85%. There was no significant difference between visual and spectrophotometric results with plasma or whole blood. The FAST-ELISA system provides a sensitive, specific, and field-adaptable test for canine visceral leishmaniasis, which can be evaluated quickly without the use of a microscope or spectrophotometer.