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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).