Skip to main content

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 2π. Peak month is equal to the parameter τ 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.