Table 2

Comparison of PCR and Microscopy for T. cruzi detection in T. infestans by developmental stage* 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

* Serrano and Carbajal not included in the analysis

N1–N5 = First to fifth nymphal stages; A = Adults; PCR = Polymerase Chain Reaction;

Discrepancy = PCR positive and Microscopy negative; NA = Non applicable

** P-value = Probability that the differences in infection rates between techniques is due to chance

Pizarro et al. BMC Infectious Diseases 2007 7:66   doi:10.1186/1471-2334-7-66