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Table 2 Relationship between results of the serological tests and sample hemolysis

From: Survey of bluetongue virus infection in free-ranging wild ruminants in Switzerland

  Score 0 Score 1 Score 2 Score 3 Total
  n = 99 n = 338 n = 829 n = 576 n = 1842
  ODP ODP ODP ODP ODP ODP ODP ODP ODP ODP
  30-49% 50-100% 30-49% 50-100% 30-49% 50-100% 30-49% 50-100% 30-49% 50-100%
Screening ELISA           
VMRDa 6 3 18 2 40 13 22 14 86 32
Confirmatory ELISAs           
VMRDb 0 3 0 0 0 3 1c 6 1c 12
BDSL 0 2 0 0 0 3 1c 4 1c 9
INGENASA 0 2 0 0 0 3 1c 3 1c 8
Serum Neutralization Test           
Titer ≥ 1:2 0 2 0 0 0 3 1 4 1 9
Total seropositive 2 0 3 5 10
Confirmed positive / screening positive (ODP ≥ 30%) 22.2% 0% 5.7% 13.9% 8.5%
Seroprevalence 2.0% 0% 0.4% 0.9% 0.5%
  1. a Cut-off at ODP 30%, b Cut-off at ODP 50%, c Unclear.
  2. Number of positive samples obtained with the screening test (VMRD ELISA) and following confirmatory tests are indicated in relation to the hemolysis serum scores (0–3) and the optical density percentage (ODP) of the screening test. One sample with ODP > 30% yielded an unclear result in the confirmatory ELISAs but to a positive result in the SNT (cut-off ≥ 1:2).