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. 2012 May;12(5):372–379. doi: 10.1089/vbz.2011.0709

FIG. 1.

FIG. 1.

The scheme of West Nile virus (WNV) serological diagnosis streamlined starting from the IgM ELISA through the IgG ELISA to the PRNT. aOptional flow of the IgG ELISA test or IFA for IgM-positive samples. bConvalescent serum is necessary for confirmatory testing. Serum is confirmed to be positive for WNV if there is a fourfold or greater increase in titer in convalescent serum. cIf a titer difference of less than fourfold in two sera is observed, the sample could be determined to be “not positive for WNV (not a case).” dIf a fourfold difference could not be demonstrated, the sample was designated as containing an antibody against an unknown (unidentified or undetermined) flavivirus. History-taking, including vaccination record, clinical signs, or medical records indicative of WNV infection, is needed to confirm a diagnosis. eConfirmed (1) positive for WNV and negative for JEV if the neutralizing antibody titer against WNV was at least fourfold greater than that of the corresponding JEV antibody titer; (2) positive for JEV and negative for WNV if the neutralizing antibody titer against JEV was at least fourfold greater than that of the corresponding antibody titer to WNV (CSF, cerebrospinal fluid; ELISA, enzyme-linked immunosorbent assay; IFA, immunofluorescence assay; IgG, immunoglobulin G; IgM, immunoglobulin M; JEV, Japanese encephalitis virus; MAC-ELISA, IgM antibody capture ELISA; PRNT, plaque reduction neutralization test; WNV, West Nile virus).