Browsing by Subject "Ixodes ricinus"

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Decoding the geography of natural TBEV microfoci in German: a geostatistical approach based on land-use patterns and climatological conditions
(2022) Borde, Johannes P.; Glaser, Rüdiger; Braun, Klaus; Riach, Nils; Hologa, Rafael; Kaier, Klaus; Chitimia-Dobler, Lidia; Dobler, Gerhard
Background: Tickborne-encephalitis (TBE) is a potentially life-threating neurological disease that is mainly transmitted by ticks. The goal of the present study is to analyze the potential uniform environmental patterns of the identified TBEV microfoci in Germany. The results are used to calculate probabilities for the present distribution of TBEV microfoci in Germany based on a geostatistical model. Methods: We aim to consider the specification of environmental characteristics of locations of TBEV microfoci detected in Germany using open access epidemiological, geographical and climatological data sources. We use a two-step geostatistical approach, where in a first step, the characteristics of a broad set of environmental variables between the 56 TBEV microfoci and a control or comparator set of 3575 sampling points covering Germany are compared using Fisher’s Exact Test. In the second step, we select the most important variables, which are then used in a MaxEnt distribution model to calculate a high resolution (400 × 400 m) probability map for the presence of TBEV covering the entire area of Germany. Results: The findings from the MaxEnt prediction model indicate that multi annual actual evapotranspiration (27.0%) and multi annual hot days (22.5%) have the highest contribution to our model. These two variables are followed by four additional variables with a lower, but still important, explanatory influence: Land cover classes (19.6%), multi annual minimum air temperature (14.9%), multi annual sunshine duration (9.0%), and distance to coniferous and mixed forest border (7.0%). Conclusions: Our findings are based on defined TBEV microfoci with known histories of infection and the repeated confirmation of the virus in the last years, resulting in an in-depth high-resolution model/map of TBEV microfoci in Germany. Multi annual actual evapotranspiration (27%) and multi annual hot days (22.5%) have the most explanatory power in our model. The results may be used to tailor specific regional preventive measures and investigations.
Identification of new microfoci and genetic characterization of tick-borne encephalitis virus isolates from Eastern Germany and Western Poland
(2024) Król, Nina; Chitimia-Dobler, Lidia; Dobler, Gerhard; Kiewra, Dorota; Czułowska, Aleksandra; Obiegala, Anna; Zajkowska, Joanna; Juretzek, Thomas; Pfeffer, Martin
(1) Background: Tick-borne encephalitis (TBE) is the most important tick-borne viral disease in Eurasia, although effective vaccines are available. Caused by the tick-borne encephalitis virus (TBEV, syn. Orthoflavivirus encephalitidis), in Europe, it is transmitted by ticks like Ixodes ricinus and Dermacentor reticulatus. TBEV circulates in natural foci, making it endemic to specific regions, such as southern Germany and northeastern Poland. Our study aimed to identify new TBEV natural foci and genetically characterize strains in ticks in previously nonendemic areas in Eastern Germany and Western Poland. (2) Methods: Ticks were collected from vegetation in areas reported by TBE patients. After identification, ticks were tested for TBEV in pools of a maximum of 10 specimens using real-time RT-PCR. From the positive TBEV samples, E genes were sequenced. (3) Results: Among 8400 ticks from 19 sites, I. ricinus (n = 4784; 56.9%) was predominant, followed by D. reticulatus (n = 3506; 41.7%), Haemaphysalis concinna (n = 108; 1.3%), and I. frontalis (n = 2; <0.1%). TBEV was detected in 19 pools originating in six sites. The phylogenetic analyses revealed that TBEV strains from Germany and Poland clustered with other German strains, as well as those from Finland and Estonia. (4) Conclusions: Although there are still only a few cases are reported from these areas, people spending much time outdoors should consider TBE vaccination.
Tick hazard in a Central European country: Mapping Europe’s principal tick-borne disease vector across Germany
(2025) Springer, Andrea; Lindau, Alexander; Fachet-Lehmann, Katrin; Kämmer, Daniel; Bulling, Ingrid; Knoll, Steffen; Król, Nina; Fischer, Dominik; Fischer, Luisa; Drehmann, Marco; Chitimia-Dobler, Lidia; Noll, Madeleine; Vineer, Hannah Rose; Kahl, Olaf; Pfeffer, Martin; Strube, Christina; Mackenstedt, Ute
The most common European tick species, Ixodes ricinus, is the principal vector of Borrelia and tick-borne encephalitis virus and several other pathogens of public health relevance in Europe. Comprehensive data on tick abundance and the underlying ecological drivers are crucial for developing awareness and control strategies and to assess future changes in tick-borne disease risk. We aimed to provide a Germany-wide map of I. ricinus abundance to aid in disease transmission risk assessment. During 2018−2020, questing tick density was assessed at 83 sites across the whole country by drag flagging, whereby 49,344 I. ricinus nymphs and adults were collected. Relationships between climate, land cover, and monthly questing I. ricinus nymph density were explored and used to draw an abundance map. Highest tick hazard was observed in areas near the coast with mild winters and moist springs, and in mid-elevation mountain ranges, which represent popular tourist destinations. The ticks’ seasonal activity pattern was predominantly unimodal. The fact that the observed regional differences are contradictory to a previous estimation based on a combination of regional studies illustrates the need for an extensive and coordinated sampling effort to reliably estimate tick abundance at larger spatial scales. Combined with data on tick-borne pathogens, our study enables estimating the density of infected ticks and consequently the risk of acquiring an infectious tick bite. Moreover, the observed relationships with climate and land cover can help to predict future developments of tick hazard under different climate scenarios in Central Europe.
Untersuchung viraler, zoonotischer Erreger in Baden-Württemberg
(2019) Lindau, Alexander; Mackenstedt, Ute
Tick-borne encephalitis (TBE) is the most common tick-borne viral infection in Germany. Tick-borne encephalitis virus (TBEV) belongs to the family Flaviviridae and is transmitted either directly by tick bites or by the alimentary route, which means by contaminated food. The main reservoir hosts of TBEV are the yellow-necked mouse and the bank vole, which is also the main reservoir host for the rodent-borne Hanta viruses. Infections with Hanta virus are mainly acquired by inhaling of aerosols of urine and faeces of infected individuals. The most common type of Hanta viruses in Southern Germany is the Puumala type. Hanta-virus infections as well as TBE infections are notifiable diseases in Germany. For both diseases the amount of registered cases per year vary between years in a contrary pattern. To be able to evaluate possible risks of TBEV for humans, it is very important to know detailed information about the epidemiology, spreading of the viruses, as well as their hosts and the viruses themselves. Therefore, the presence of TBEV-foci, as well as the breakdown into micro- and macrofoci was addressed. Additionally, the prevalence of Hantavirus in rodents was studied.