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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