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Table 2 Estimates for the parameters in the model describing the densities of questing larval, nymphal and adult Ixodes ricinus 2006 – 2009

From: Circumstantial evidence for an increase in the total number and activity of borrelia-infected ixodes ricinus in the Netherlands

Sampling locations

Baseline tick density/activity

Population trend

Month of peak tick density/activity

Tick aggregation

P-value

Appelscha

1.5

1.5

6.1

2.7

<0.01

Bilthoven

3.4

0.0

6.7

1.4

0.07

Ede

45.0

11.9

6.4

1.1

0.05

Eijsden

10.7

0.0

6.1

1.1

0.08

Gieten

5.5

18.4

6.2

0.5

<0.01

Hoog Baarlo

67.4

−11.4

6.6

1.1

<0.01

Kwade hoek

3.5

0.0

6.4

0.4

1.00

Montferland

25.2

0.0

6.7

0.4

0.09

Schiermonnikoog

1.5

3.4

6.8

0.5

0.02

Twiske

22.0

0.0

6.0

0.7

0.30

Vaals

10.0

0.0

6.5

0.2

0.64

Veldhoven

32.8

0.0

6.7

0.7

0.11

Wassenaar

0.0

6.2

5.8

0.4

<0.01

  1. Increasing trends are indicated by positive estimates for the coefficient b in the linear function (Experimental procedures), decreasing trends by negative estimates. Baseline is equal to the intercept a in the linear function describing the tick density/activity per drag area. Population trend is the change in tick density/activity per year; it is equal to the coefficient b in the linear function multiplied by 2Ï€. Peak month is equal to the parameter Ï„ in the cosine function describing the annual seasonality. Tick aggregation is equal to the parameter k in the negative binomial distribution. Estimates are maximum likelihood estimates for each sampling location. Study sites with significant trends are shown in bold.