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Type of publication: Journal Article
Type of document: Full Paper

Year: 2016

Authors: Brugger, K; Boehnke, D; Petney, T; Dobler, G; Pfeffer, M; Silaghi, C; Schaub, GA; Pinior, B; Dautel, H; Kahl, O; Pfister, K; Süss, J; Rubel, F

Title: A Density Map of the Tick-Borne Encephalitis and Lyme Borreliosis Vector Ixodes ricinus (Acari: Ixodidae) for Germany.

Source: J Med Entomol (53), 6 1282-1302.

Authors Vetmeduni Vienna:

Brugger Katharina
Conrady Beate
Rubel Franz

Vetmed Research Units
Institute of Food Safety, Food Technology and Veterinary Public Health, Unit of Veterinary Public Health and Epidemiology

The castor bean tick Ixodes ricinus (L.) is the principal vector for a variety of viral, bacterial, and protozoan pathogens causing a growing public-health issue over the past decades. However, a national density map of I. ricinus is still missing. Here, I. ricinus nymphs in Germany were investigated by compiling a high-resolution map depicting the mean annually accumulated nymphal density, as observed by monthly flagging an area of 100 m2 Input data comprise ticks collected at 69 sampling sites. The model domain covers an area of about 357,000 km2 (regional scale). Two negative binomial regression models were fitted to the data to interpolate the tick densities to unsampled locations using bioclimatic variables and land cover, which were selected according to their significance by the Akaike information criterion (AIC). The default model was fitted to the complete dataset resulting in AIC = 842. An optimized model resulted in a significantly better value of AIC = 732. Tick densities are very low in urban (green) areas. Maximum annual densities up to 1,000 nymphs per 100 m2 are observed in broad-leaved forests. The tick maps were verified by leave-one-out cross-validation. Root mean square errors of RMSE = 137 and RMSE = 126 nymphs per 100 m2 were estimated for the two models, respectively. These errors are of the order of the interannual variation of the tick densities. The compilation of a high-resolution density map of unfed nymphal I. ricinus for Germany provides a novel, nationwide insight into the distribution of an important disease vector.© The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email:

Keywords Pubmed: Animal Distribution
Arachnid Vectorsmicrobiologyphysiology
Encephalitis, Tick-Bornetransmission
Ixodesgrowth & developmentmicrobiologyphysiology
Lyme Diseasetransmission
Models, Biological
Population Density

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