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Table 1 Expected Observed Risk Ratios and Case Ratios and Proportion of False Positive Cases of Zika Virus Infection During an Outbreak, by Type of Surveillance, Increase in Infection Risk, and Case Definition Sensitivity and Specificity

From: An assessment of public health surveillance of Zika virus infection and potentially associated outcomes in Latin America

 

RRZ0→1a

Case definition sensitivity

Case definition specificity

Expected observed risk ratio

Expected observed case ratio

False positive proportion

Regular surveillanceb

1

2.0

95.9

1.00

0.90

94.89

2

2.0

95.9

0.95

0.85

92.27

5

2.0

95.9

0.78

0.70

83.52

8

2.0

95.9

0.62

0.56

73.11

Enhanced surveillancec

1

9.8

79.7

1.00

0.90

94.89

2

9.8

79.7

0.95

0.85

92.27

5

9.8

79.7

0.78

0.70

83.52

8

9.8

79.7

0.62

0.56

73.11

Serologic surveillanced

1

37.7

81.1

1.00

0.90

81.86

2

37.7

81.1

1.09

0.98

74.36

5

37.7

81.1

1.36

1.23

55.17

8

37.7

81.1

1.63

1.47

39.77

  1. aHypothetical Relative Increase in Infection Risk (RRZ0 → 1); bSurveillance case definition and demand of health care similar to those observed in Yap Island [11]; cSurveillance case definition similar to the one used in Yap Island with a five-fold increase in the demand of health care (detection probability); d Surveillance based of serologic surveys of random samples of the population