Which titer level does the A. phagocytophilum portion of the SNAP 4Dx Test correlate to?
• IFA and the SNAP 4Dx Test are two different types of assays. IFA uses a whole-cell preparation containing A. phagocytophilum organisms grown in cell culture. The SNAP 4Dx Test is an ELISA assay that uses a well-defined peptide to detect antibodies to A. phagocytophilum. Measurement of the antibody response on these two types of tests is very different. Interpretation of an IFA test result is more subjective and, therefore, requires substantial expertise by the testing laboratory. In general, a sample testing positive for A. phagocytophilum on the SNAP 4Dx Test has a good correlation with a positive IFA test result. • The test has also been shown to cross-react with another Anaplasma species, known as A. platys. In an internal IDEXX study involving dogs infected with a laboratory strain of A. platys, the SNAP 4Dx Test was reactive with serum from 10 out of 10 dogs.
