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Table 4 Results of duplicate runs at cut offs Ct 40 and 35 for aprV2 and aprB2 rtPCR in 297 clinically healthy sheep and 21 sheep with foot lesions from 10 flocks considered free of footrot

From: Assessment of a rtPCR for the detection of virulent and benign Dichelobacter nodosus, the causative agent of ovine footrot, in Australia

Foot lesion

Cut off 40

Cut off 35

Run 1 + ve

Run 1 -ve

Run 2 + ve

Run 2 -ve

Run 1 + ve

Run 1 -ve

Run 2 + ve

Run 2 -ve

aprB2

 Positive

0

21

2

19

0

21

0

21

 Negative

18

279

10

287

4

293

4

293

 Specificity

 

93.90%

 

96.60%

 

98.70%

 

98.70%

 McNemars two tailed p value

 

0.7488

 

0.1374

 

0.0014

 

0.0014

aprB2 cut off agreement

 Run 2 + ve

5

7

  

4

0

  

 Run 2 -ve

13

293

  

0

314

  

 Kappa

0.302

“fair”

  

1

“perfect”

  

aprV2

 Positive

4

17

4

17

4

17

4

17

 Negative

10

287

15

282

5

292

5

292

 Specificity

 

96.60%

 

94.90%

 

98.30%

 

98.30%

 McNemars two tailed p value

 

0.2482

 

0.8597

 

0.019

 

0.019

aprV2 cut off agreement

 Run 2 + ve

12

7

  

9

0

  

 Run 2 -ve

2

297

  

0

309

  

 Kappa

0.713

“good”

  

1

“perfect”

  
  1. Specificity is shown along with p-value for McNemar’s test for independence between lesion score and rtPCR result, and kappa statistic for agreement between rtPCR runs