A comparative evaluation of a new immunoenzymatic test (RREID) with currently used diagnostic tests (DME and FAT) for dog rabies.

Diagnosis of rabies in dogs was performed in microplates which had been coated with immunoglobulin G previously sensitized to purified rabies virus antinucleocapsids. Homogenized brain suspensions were incubated in the plates and the specific binding rabies antigen was revealed by the use of the same IgG conjugated with horseradish peroxidase. Samples from the same specimens were subjected to standard rabies diagnostic tests--the direct microscopic examination (DME) or Sellers staining for Negri bodies and the fluorescent antibody test (FAT). FAT was used as the reference test or gold standard because of its proven sensitivity and accuracy. The concordance of FAT with RREID was 98.89% while that with DME was 96.67%. Sensitivity of both DME and RREID compared with FAT in this study was 100% while specificity of RREID versus FAT was 98.46% as compared with 95.38% DME versus FAT. The positive predictive value of RREID versus FAT was 96.15% while that of DME versus FAT was 89.29% although the negative predictive value of both RREID and DME compared with FAT was 100%. In the overall assessment, RREID results were demonstrated to approximate closely those of FAT. It is therefore concluded that RREID can be used in diagnostic laboratories to corroborate DME and where MIT and FAT cannot be done. RREID would also be useful in epidemiological studies where large samples are tested.