title: Second external quality assessment of the molecular diagnostic of West Nile virus: are there improvements towards the detection of WNV?
abstract: BACKGROUND
  WNV epidemics occur worldwide, new WNV isolates were isolated in southern-east Europe belonging to WNV lineage 2. A first international proficiency study on WNV indicted that some laboratories were not able to detect WNV lineage 2 virus genome by their PCR diagnostic assays. Therefore an actual External Quality Assessment with both virus lineages was performed to monitor the improvements in molecular diagnostics.
  
  
  OBJECTIVE
  To asses the proficiency of laboratories to detect West Nile virus with molecular diagnostic tests.
  
  
  METHODS
  A test panel of different WNV isolates and virus dilutions was given to 26 laboratories to test the samples with their routine diagnostic methods.
  
  
  RESULTS
  Twenty-one participating laboratories provided 28 data set results. WNV lineage 1 was detected with high overall efficiency of 92% (67.9-100%) but two different WNV lineage 2 strains were detected at lower rates (mean = 73%, 67.9-75%) by the different PCR assays. 93% of the laboratories were able to detect a WNV lineage 1 with a concentration of 1.2×10(4)copies/ml but the detection rate was decreased to 68% for 1.2×10(3)copies/ml. One laboratory generated false-positive result from the non-virus control samples and 29% of the datasets showed false-positive results for non-WNV flavivirus samples.
  
  
  CONCLUSIONS
  The WNV EQA showed an improved proficiency of laboratories as compared to the first EQA. However, the data suggest that problems in the detection of both lineages were still present since the first proficiency test was performed in 2006. Further proceedings versus the detection of both lineages are needed particularly for in-house assays.
authors: Robert Koch Institute, Nordufer 20, 12353 Berlin, Germany.
authors: Sonja
authors: S
authors: Linke
authors: William G
authors: WG
authors: Mackay
authors: Calum
authors: C
authors: Scott
authors: Paul
authors: P
authors: Wallace
authors: Matthias
authors: M
authors: Niedrig
mesh_terms: D003951:Diagnostic Errors; D006801:Humans; D007753:Laboratories / Q000592:standards; D059021:Laboratory Proficiency Testing; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D057089:Pathology, Molecular; D011786:Quality Control; D012680:Sensitivity and Specificity; D014901:West Nile Fever / Q000175:diagnosis* / Q000453:epidemiology; D014902:West Nile virus / Q000235:genetics / Q000302:isolation & purification*