title: First international external quality assessment study on molecular and serological methods for yellow fever diagnosis.
abstract: OBJECTIVE
  We describe an external quality assurance (EQA) study designed to assess the efficiency and accurateness of molecular and serological methods used by expert laboratories performing YF diagnosis.
  
  
  METHODS
  For molecular diagnosis evaluation, a panel was prepared of 14 human plasma samples containing specific RNA of different YFV strains (YFV-17D, YFV South American strain [Brazil], YFV IvoryC1999 strain), and specificity samples containing other flaviviruses and negative controls. For the serological panel, 13 human plasma samples with anti-YFV-specific antibodies against different strains of YFV (YFV-17D strain, YFV IvoryC1999 strain, and YFV Brazilian strain), as well as specificity and negative controls, were included.
  
  
  RESULTS
  Thirty-six laboratories from Europe, the Americas, Middle East, and Africa participated in these EQA activities. Only 16% of the analyses reported met all evaluation criteria with optimal performance. Serial dilutions of YFV-17D showed that in general the methodologies reported provided a suitable sensitivity. Failures were mainly due to the inability to detect wild-type strains or the presence of false positives. Performance in the serological diagnosis varied, mainly depending on the methodology used. Anti-YFV IgM detection was not performed in 16% of the reports using IIF or ELISA techniques, although it is preferable for the diagnosis of YFV acute infections. A good sensitivity profile was achieved in general; however, in the detection of IgM antibodies a lack of sensitivity of anti-YFV antibodies against the vaccine strain 17D was observed, and of the anti-YFV IgG antibodies against a West African strain. Neutralization assays showed a very good performance; however, the unexpected presence of false positives underlined the need of improving the running protocols.
  
  
  CONCLUSIONS
  This EQA provides information on each laboratory's efficacy of RT-PCR and serological YFV diagnosis techniques. The results indicate the need for improving serological and molecular diagnosis techniques and provide a follow-up of the diagnostic profiles.
authors.affiliation: Centre for Biological Security, Robert Koch Institute, Berlin, Germany. Domingo-CarrascoC@rki.de
authors.forename: Cristina
authors.initials: C
authors.lastname: Domingo
authors.forename: Camille
authors.initials: C
authors.lastname: Escadafal
authors.forename: Leonid
authors.initials: L
authors.lastname: Rumer
authors.forename: Jairo A
authors.initials: JA
authors.lastname: Méndez
authors.forename: Paquita
authors.initials: P
authors.lastname: García
authors.forename: Amadou A
authors.initials: AA
authors.lastname: Sall
authors.forename: Anette
authors.initials: A
authors.lastname: Teichmann
authors.forename: Oliver
authors.initials: O
authors.lastname: Donoso-Mantke
authors.forename: Matthias
authors.initials: M
authors.lastname: Niedrig
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D006801:Humans; D059021:Laboratory Proficiency Testing; D025202:Molecular Diagnostic Techniques / Q000379:methods / Q000592:standards*; D011785:Quality Assurance, Health Care; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000592:standards*; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods / Q000592:standards*; D014709:Vero Cells; D019562:Viral Load; D015004:Yellow Fever / Q000175:diagnosis* / Q000276:immunology / Q000821:virology; D015005:Yellow fever virus / Q000235:genetics / Q000276:immunology