title: A Density Map of the Tick-Borne Encephalitis and Lyme Borreliosis Vector Ixodes ricinus (Acari: Ixodidae) for Germany.
abstract: 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 m2Input 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 m2are 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 m2were 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.
authors: Institute for Veterinary Public Health, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria (katharina.brugger@vetmeduni.ac.at; beate.pinior@vetmeduni.ac.at; franz.rubel@vetmeduni.ac.at) katharina.brugger@vetmeduni.ac.at.
authors: Katharina
authors: K
authors: Brugger
authors: Institute of Geography and Geoecology, Karlsruhe Institute of Technology, Reinhard-Baumeister-Platz 1, 76131 Karlsruhe, Germany (denise.boehnke@kit.edu).
authors: Denise
authors: D
authors: Boehnke
authors: Institute of Zoology, Department of Ecology and Parasitology, Karlsruhe Institute of Technology, Kornblumen Straße 13, 76131 Karlsruhe, Germany (trevor.petney@kit.edu).
authors: Trevor
authors: T
authors: Petney
authors: Bundeswehr Institute of Microbiology, Neuherbergstraße 11, 80937 Munich, Germany (gerharddobler@bundeswehr.org).
authors: Gerhard
authors: G
authors: Dobler
authors: Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, An den Tierkliniken 1, Leipzig, Germany (pfeffer@vetmed.uni-leipzig.de).
authors: Martin
authors: M
authors: Pfeffer
authors: Institute of Parasitology, National Center of Vector Entomology, University of Zurich, Winterthurerstraße 266a, 8057 Zurich, Switzerland (cornelia.silaghi@uzh.ch).
authors: Cornelia
authors: C
authors: Silaghi
authors: Group Zoology/Parasitology, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany (guenter.schaub@rub.de).
authors: Günter A
authors: GA
authors: Schaub
authors: Institute for Veterinary Public Health, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria (katharina.brugger@vetmeduni.ac.at; beate.pinior@vetmeduni.ac.at; franz.rubel@vetmeduni.ac.at).
authors: Beate
authors: B
authors: Pinior
authors: Tick-Radar GmbH, Haderslebener Straße 9, 12163 Berlin, Germany (dautel@tick-radar.de; olaf.kahl@berlin.de).
authors: Hans
authors: H
authors: Dautel
authors: Tick-Radar GmbH, Haderslebener Straße 9, 12163 Berlin, Germany (dautel@tick-radar.de; olaf.kahl@berlin.de).
authors: Olaf
authors: O
authors: Kahl
authors: Comparative Tropical Medicine and Parasitology, Ludwig-Maximilians-Universität München, Leopoldstraße 5, 80752 Munich, Germany (kurt.pfister@tropa.vetmed.uni-muenchen.de).
authors: Kurt
authors: K
authors: Pfister
authors: Tick Information Center, Lindenstraße 35, 07646 Lippersdorf, Germany (jochen_suess@t-online.de).
authors: Jochen
authors: J
authors: Süss
authors: Institute for Veterinary Public Health, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria (katharina.brugger@vetmeduni.ac.at; beate.pinior@vetmeduni.ac.at; franz.rubel@vetmeduni.ac.at).
authors: Franz
authors: F
authors: Rubel
mesh_terms: D063147:Animal Distribution; D000818:Animals; D001096:Arachnid Vectors / Q000382:microbiology / Q000502:physiology*; D004675:Encephalitis, Tick-Borne / Q000635:transmission; D005858:Germany; D018884:Ixodes / Q000254:growth & development / Q000382:microbiology / Q000502:physiology*; D008193:Lyme Disease / Q000635:transmission; D008954:Models, Biological; D009758:Nymph / Q000382:microbiology / Q000502:physiology; D011156:Population Density
keywords: Ixodes ricinus; climate; general linear model; ixodid tick; population density