Evaluation of dot enzyme-linked immunosorbent assay (dot-ELISA) for the serodiagnosis of canine leishmaniosis as compared with indirect immunofluorescence assay.

A dot enzyme-linked immunosorbent assay (dot-ELISA) was developed and compared with a standard indirect immunofluorescence assay (IFA) for the rapid serodiagnosis of canine leishmaniosis. The two tests were used to examine sera from Leishmania infantum-infected and control dogs. Using the dot-ELISA, 137 of 149 sera (91.9%) from infected animals gave a clearly positive reaction, whereas in the standard IFA technique 147 (98.7%) were positive at a reciprocal titer of 40 or over (titer range 40-10,240). Control sera from 75 healthy dogs, not living in endemic areas, and 11 dogs with other diseases (babesiosis, cryptococcosis, ehrlichiosis, dermatitis, and chronic hepatitis) but Leishmania-negative were used to determine the specificity of the assays. All the sera were negative with IFA (100%), whereas using the dot-ELISA only 74 sera (86%) from controls gave a negative result. In the standard IFA no cross-reactivity was noted, in the dot-ELISA a weak cross-reaction was observed with a serum sample from a dog with babesiosis. The interpretation of dot-ELISA could be easily performed by visual inspection of the nitrocellulose disks. The most remarkable feature of dot-ELISA was the high sensitivity (91.9%) and positive predictive value (92.6%), even if the test showed a specificity lower than IFA. Because of its easy performance and high sensitivity, the dot-ELISA may be a useful test to be executed in the field for the diagnosis of canine leishmaniosis.