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Table 4 Inter-rater agreement (Kappa value) between ELISA kits for detection of antibodies against T. gondii (ID Screen® Toxoplasmosis Indirect) or N. caninum (ID Screen® Neospora caninum indirect multi-species and ID Screen® Neospora caninum Competition) and immunoblot, and between ELISA kits (ID Screen® Neospora caninum Indirect Multi-species and ID Screen® Neospora caninum Competition)

From: Toxoplasma gondii and Neospora caninum infections in South American camelids in Switzerland and assessment of serological tests for diagnosis

   TOXO-MS (manufacturer’s cut-offs) TOXO-MS (optimized cut-off)  
Positive Doubtful Negative Total Positive Doubtful Negative Total  
T. gondii immunoblot Positive 80 3 8 91 86 0 5 91  
Doubtful 0 0 0 0 0 0 0 0  
Negative 1 0 94 95 2 0 93 95  
Total 81 3 102 186 88 0 98 186  
Kappa (κ) 0.873    0.925    
SE of κ 0.035    0.028    
95% CI 0.804–0.941   0.870–0.979   
Weighted κ 0.887    0.925    
   NCS-MS (manufacturer’s cut-offs) NCS-MS (optimized cut-off)  
Positive Doubtful Negative Total Positive Doubtful Negative Total  
N. caninum immunoblot Positive 19 5 4 28 25 0 3 28  
Doubtful 0 0 2 2 0 0 2 2  
Negative 0 0 76 76 0 0 76 76  
Total 19 5 82 106 25 0 81 106  
Kappa (κ) 0.739     0.879     
SE of κ 0.066     0.052     
95% CI 0.610–0.868   0.777–0.981   
Weighted κ 0.806     0.901     
   NCC (manufacturer’s cut-offs) NCC (optimized cut-off)  
Positive Doubtful Negative Total Positive Doubtful Negative Total  
N. caninum immunoblot Positive 21 5 2 28 26 0 2 28  
Doubtful 1 1 0 2 2 0 0 2  
Negative 0 0 76 76 1 0 75 76  
Total 22 6 78 106 29 0 77 106  
Kappa (κ) 0.819     0.884     
SE of κ 0.055     0.049     
95% CI 0.710–0.927   0.788–0.980   
Weighted κ 0.876     0.905     
  A NCC (manufacturer’s cut-offs) B NCC (optimized cut-off)
Positive Doubtful Negative Total Positive Doubtful Negative Total
NCS-MS (A: manufacturer’s cut-off
B: optimized cut-off)
Positive 18 1 0 19   26 0 0 26
Doubtful 3 2 0 5   0 0 0 0
Negative 1 3 78 82   3 0 77 80
Total 22 6 78 106   29 0 77 106
Kappa (κ) 0.807      0.926    
SE of κ 0.060      0.042    
95% CI 0.689–0.925    0.845–1.000  
Weighted κ 0.876      0.926    
  1. TOXO-MS: ID Screen® Toxoplasmosis Indirect; NCS-MS: ID Screen® Neospora caninum Indirect Multi-species ELISA; NCC: ID Screen® Neospora caninum Competition; SE: Standard Error; CI : Confidence Interval