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Table 2 Comparison of PCR and Microscopy for T. cruzi detection in T. infestans by developmental stage* in Chuquisaca, Bolivia

From: PCR reveals significantly higher rates of Trypanosoma cruzi infection than microscopy in the Chagas vector, Triatoma infestans: High rates found in Chuquisaca, Bolivia

Stage PCR % Microscopy % Sample size P-value** Discrepancy % Kappa s.e.
N1 80.00 60.00 10 0.05 20.00 0.54 0.26
N2 80.00 48.00 25 0.02 32.00 0.37 0.14
N3 82.61 47.83 23 0.03 34.78 0.32 0.14
N4 100.00 50.00 6 0.39 50.00 NA NA
N5 80.00 70.00 30 <0.0001 10.00 0.74 0.14
A 79.55 56.82 40 0.0002 24.44 0.38 0.13
Total 81.16 56.52 138 <0.0001 24.64 0.43 0.07
Sensitivity 100.00 69.64   <0.0001    
  1. * Serrano and Carbajal not included in the analysis
  2. N1–N5 = First to fifth nymphal stages; A = Adults; PCR = Polymerase Chain Reaction;
  3. Discrepancy = PCR positive and Microscopy negative; NA = Non applicable
  4. ** P-value = Probability that the differences in infection rates between techniques is due to chance