Browsing by Person "Kaier, Klaus"

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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.
The emergence and dynamics of tick-borne Encephalitis Virus in a new endemic region in Southern Germany
(2022) Lang, Daniel; Chitimia-Dobler, Lidia; Bestehorn-Willmann, Malena; Lindau, Alexander; Drehmann, Marco; Stroppel, Gabriele; Hengge, Helga; Mackenstedt, Ute; Kaier, Klaus; Dobler, Gerhard; Borde, Johannes
Tick-borne encephalitis (TBE) is the most important viral tick-borne infection in Europe and Asia. It is emerging in new areas. The mechanisms of emergence are fairly unknown or speculative. In the Ravensburg district in southern Germany, TBE emerged, mainly over the last five years. Here, we analyzed the underlying epidemiology in humans. The resulting identified natural foci of the causal TBE virus (TBEV) were genetically characterized. We sampled 13 potential infection sites at these foci and detected TBEV in ticks (Ixodes ricinus) at eight sites. Phylogenetic analysis spurred the introduction of at least four distinct TBEV lineages of the European subtype into the Ravensburg district over the last few years. In two instances, a continuous spread of these virus strains over up to 10 km was observed.
Serological protection rates against TBEV infection in blood donors from a highly endemic region in Southern Germany
(2023) Dobler, Gerhard; Euringer, Kathrin; Kaier, Klaus; Borde, Johannes P.
Background: Tick-borne encephalitis (TBE) is the most significant tick-borne disease in Europe and Asia, with more than 10,000 cases per year worldwide. A surge of reported TBE cases can be observed despite the availability of highly efficient vaccines. There is little known about the serological immune protection rate of the population in Germany. The seroprotection rate is defined as the presence of neutralizing antibodies. In contrast, the vaccination rate, as defined by public health agencies, may differ from the true protection rate in a population. Materials and Methods: 2220 blood samples from inhabitants of the county Ortenaukreis in the Federal State of Baden-Württemberg in Germany were included in the study. These were tested for anti-TBEV IgG antibodies by an anti-TBEV-IgG-ELISA. Subsequently, all TBEV-IgG positive samples were confirmed for neutralizing antibodies in the micro serum neutralization assay. Results: From the overall 2220 samples, 2104 were included in the comparison because of the selection of specific age groups (ages 20–69). In our sample size, we found an average serological protection rate (presence of neutralizing antibodies) of 57% (518/908) for the female blood donors and of 52% (632/1196) for the male blood donors. Discussion: In this study, we present new findings on a highly endemic region in southern Germany. Additionally, we present current data regarding the serological TBEV protection rates in the Ortenaukreis in southern Germany and compare these with a dataset published by the RKI, which is based on vaccination reports of the primary care providers and health care insurers, and with a self-reporting study conducted by a vaccine manufacturer. Our results significantly exceed the official numbers of average active vaccination status by 23.2% for females and by 21% for males. This might indicate an even longer persistence of TBE-vaccination-induced antibody titers than previously assumed.