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Table 3 Effect of 15% DEET repellent over time, treatment, position, and person on Anopheles arabiensis in a four-hour repellent evaluation in the Mbingu village

From: Use of a semi-field system to evaluate the efficacy of topical repellents under user conditions provides a disease exposure free technique comparable with field data

Treatments

Hours

Incidence rate ratio (IRR)1[95% CI]

Z-test statistic2

P-value3

15% DEET in lotion format

1

-

-

-

2

0.403 [0.083-1.956]

−1.13

0.260

3

0.326 [0.068-1.550]

−1.41

0.159

4

0.722 [0.185-2.812]

−0.47

0.639

15% DEET in ethanol

1

-

-

-

2

1.229 [0.343-4.399]

0.32

0.750

3

1.963 [0.583-6.621]

1.09

0.277

4

1.370 [0.400-4.693]

0.86

0.500

Treatments

    

Placebo

-

-

-

-

15% DEET in lotion format

-

0.171 [0.063-0.467]

−3.45

0.001

15% DEET in ethanol

-

0.165 [0.062-0.441]

−3.59

<0.0001

Position

    

1

-

-

-

-

2

-

0.932 [0.542-1.602]

−0.25

0.800

3

-

1.262 [0.750-2.126]

0.88

0.380

Person

    

1

-

-

-

-

2

-

2.660 [1.420-4.979]

3.06

0.002

3

-

1.801 [0.924-3.510]

1.73

0.084

4

-

0.381 [0.127-1.141]

−1.72

0.085

5

-

0.328 [0.106-1.015]

−1.93

0.053

6

-

0.262 [0.081-0.841]

−2.25

0.025

  1. 1The data for position one, person one and effect of treatments in hour one were used as a reference values for calculating the incidence rate ratios (IRR) for mosquito bites. 2The test statistic z is the ratio of the Coefficient to the Standard error of that respective predictor and is used to test against a two-sided alternative hypothesis that the Coefficient is not equal to zero. 3The probability (P) that a particular z test statistic is different to what has been observed under the null hypothesis.