Results of the EQA study for laboratories performing IFA for the serological detection of West Nile virus.

WNV: West Nile virus; DENV: dengue virus; JEV; Japanese encephalitis virus; TBEV: tick-borne encephalitis virus; USUV: Usutu virus; Neg: negative control; Sc: Score; IgM: Immunoglobulin M; IgG: Immunoglobulin G; nd: not done; *: reactivity also with heterologous flaviviruses; E: commercial IFA Euroimmun; H: IFA in-house test; S: commercial IFA Scimedx.