Habitat properties are key drivers of Borrelia burgdorferi (s.l.) prevalence in Ixodes ricinus populations of deciduous forest fragments.

BACKGROUND: The tick Ixodes ricinus has considerable impact on the health of humans and other terrestrial animals because it transmits several tick-borne pathogens (TBPs) such as B. burgdorferi (sensu lato), which causes Lyme borreliosis (LB). Small forest patches of agricultural landscapes provide many ecosystem services and also the disservice of LB risk. Biotic interactions and environmental filtering shape tick host communities distinctively between specific regions of Europe, which makes evaluating the dilution effect hypothesis and its influence across various scales challenging. Latitude, macroclimate, landscape and habitat properties drive both hosts and ticks and are comparable metrics across Europe. Therefore, we instead assess these environmental drivers as indicators and determine their respective roles for the prevalence of B. burgdorferi in I. ricinus. METHODS: We sampled I. ricinus and measured environmental properties of macroclimate, landscape and habitat quality of forest patches in agricultural landscapes along a European macroclimatic gradient. We used linear mixed models to determine significant drivers and their relative importance for nymphal and adult B. burgdorferi prevalence. We suggest a new prevalence index, which is pool-size independent. RESULTS: During summer months, our prevalence index varied between 0 and 0.4 per forest patch, indicating a low to moderate disservice. Habitat properties exerted a fourfold larger influence on B. burgdorferi prevalence than macroclimate and landscape properties combined. Increasingly available ecotone habitat of focal forest patches diluted and edge density at landscape scale amplified B. burgdorferi prevalence. Indicators of habitat attractiveness for tick hosts (food resources and shelter) were the most important predictors within habitat patches. More diverse and abundant macro- and microhabitat had a diluting effect, as it presumably diversifies the niches for tick-hosts and decreases the probability of contact between ticks and their hosts and hence the transmission likelihood. CONCLUSIONS: Diluting effects of more diverse habitat patches would pose another reason to maintain or restore high biodiversity in forest patches of rural landscapes. We suggest classifying habitat patches by their regulating services as dilution and amplification habitat, which predominantly either decrease or increase B. burgdorferi prevalence at local and landscape scale and hence LB risk. Particular emphasis on promoting LB-diluting properties should be put on the management of those habitats that are frequently used by humans. In the light of these findings, climate change may be of little concern for LB risk at local scales, but this should be evaluated further.

Molecular identification of novel phlebovirus sequences in European ticks.

In recent years the number of newly described tick-borne phleboviruses has been steadily growing. Some of these novel viruses are highly pathogenic in humans, e.g. the Heartland and severe fever with thrombocytopenia syndrome virus. We aimed to analyse ticks sampled across Europe to investigate the diversity of phleboviruses using a comprehensive PCR-based screening approach. A total of 4387 ticks were collected from the vegetation in regions of France, Belgium, Germany, Sweden, and Estonia, respectively. Ticks were pooled and 22/979 pools tested positive using a PCR targeting the large (L) segment of phleboviruses. Phylogenetic analysis of a 500-bp fragment of the L segment showed a distinct novel clade provisionally named Glabbeek/Osterholz group (Belgium and Germany). In addition, sequences from ticks sampled in France clustered together with the recently described Antigone virus from Greece and AnLuc from Portugal. Our results extend the current diversity of phleboviruses in Europe. Future research should address the ecological processes driving the occurrence of phleboviruses and the impact of these novel phleboviruses for public health.

Affect-related personality traits and contextual interference processing during perception of facial affect.

We investigated the influence of different personality dimensions on neural emotional conflict processing. A cluster analysis separated two different subsamples of subjects. One sample scored high on neuroticism, anxiety, depressivity and low on extraversion and was found to be highly sensitive to emotional conflicts during processing of negative and positive expressions. This sample revealed increased conflict induced activation in the amygdala during processing of negative expressions which was associated with higher levels of anxiety and depressivity. This amygdala activity was positively coupled with activity in dACC during processing of neutral expressions and negatively coupled in the sample with opposite personality scores. Depressivity was also associated with activation in subgenual ACC. Increased activation in subgenual ACC was also found during processing of positive expressions. This activation as well as activation in rostral ACC was higher in lower extraversion scores. In summary, individuals with higher neuroticism, anxiety, depressivity scores and low extraversion scores are sensitive to emotional conflicts during the processing of emotional expressions. Furthermore, emotional conflict resolution might challenge emotional regulative mechanisms in these subjects which became evident by increased activations in different subregions of the ACC.