Validation of a commercially available cELISA test for canine neosporosis against an indirect fluorescent antibody test (IFAT)

A commercially available competitive enzyme-linked immunosorbent assay (cELISA, VMRD (R)) was validated for the detection of Neospora caninum antibodies in the serum of dogs, using as a reference test an indirect fluorescent antibody test (IFAT, Fuller (R)). A partial verification approach Was used. A total of 618 dogs were screened with cELISA and a subset of positive and negative sera (n = 237) were then tested with IFAT. Naive relative sensitivity (SE,) and naive relative specificity (SPnv) of cELISA were calculated and then corrected (SEcorr SPcorr) for studies with partial validation. Results showed a SEnv of 72% and a SPnv of 89.3%; corrected estimates showed a SEcorr of 47% and a SPcorr of 96%. ROC analysis showed that the cutoff recommended by the Manufacturer (30%) corresponded to the highest naive sensitivity (72%) combined with a good naive specificity (90%) of cELISA. Corrected estimates of SE and SP for partial verification method revealed that SE of the cELISA is lower and SP is higher than naive estimates. The results Suggest to use this test for confirmation of a clinical suspicion of neosporosis, and to use some techniques for adjustment of misclassification in prevalence and risk-factor studies.