Tick range expansion to higher elevations: does Borrelia burgdorferi sensu lato facilitate the colonisation of marginal habitats?

BACKGROUND: Parasites can alter host and vector phenotype and thereby affect ecological processes in natural populations. Laboratory studies have suggested that Borrelia burgdorferi sensu lato, the causative agent of human Lyme borreliosis, may induce physiological and behavioural alterations in its main tick vector in Europe, Ixodes ricinus, which increase the tick's mobility and survival under challenging conditions. These phenotypic alterations may allow I. ricinus to colonise marginal habitats ('facilitation hypothesis'), thereby fuelling the ongoing range expansion of I. ricinus towards higher elevations and latitudes induced by climate change. To explore the potential for such an effect under natural conditions, we studied the prevalence of B. burgdorferi s.l. in questing I. ricinus and its variation with elevation in the Swiss Alps. RESULTS: We screened for B. burgdorferi s.l. infection in questing nymphs of I. ricinus (N = 411) from 15 sites between 528 and 1774 m.a.s.l to test if B. burgdorferi s.l. prevalence is higher at high elevations (i.e. in marginal habitats). Opposite of what is predicted under the facilitation hypothesis, we found that B. burgdorferi s.l. prevalence in I. ricinus nymphs decreased with increasing elevation and that Borrelia prevalence was 12.6% lower in I. ricinus nymphs collected at the range margin compared to nymphs in the core range. But there was no association between Borrelia prevalence and elevation within the core range of I. ricinus. Therefore the observed pattern was more consistent with a sudden decrease in Borrelia prevalence above a certain elevation, rather than a gradual decline with increasing elevation across the entire tick range. CONCLUSIONS: In conclusion, we found no evidence that B. burgdorferi s.l.-induced alterations of I. ricinus phenotype observed in laboratory studies facilitate the colonisation of marginal habitats in the wild. Rather, ticks in marginal habitats are substantially less likely to harbour the pathogen. These findings have implications for a better understanding of eco-evolutionary processes in natural host-parasite systems, as well as the assessment of Lyme borreliosis risk in regions where I. ricinus is newly emerging.

Elevational Changes in Bacterial Microbiota Structure and Diversity in an Arthropod-Disease Vector.

Environmental conditions change rapidly along elevational gradients and have been found to affect community composition in macroscopic taxa, with lower diversity typically observed at higher elevations. In contrast, microbial community responses to elevation are still poorly understood. Specifically, the effects of elevation on vector-associated microbiota have not been studied to date, even though the within-vector microbial community is known to influence vector competence for a range of zoonotic pathogens. Here we characterize the structure and diversity of the bacterial microbiota in an important zoonotic disease vector, the sheep tick Ixodes ricinus, along replicated elevational gradient (630-1673 m) in the Swiss Alps. 16S rRNA sequencing of the whole within-tick bacterial microbiota of questing nymphs and adults revealed a decrease in Faith's phylogenetic microbial alpha diversity with increasing elevation, while beta diversity analyses revealed a lower variation in microbial community composition at higher elevations. We also found a higher microbial diversity later in the season and significant differences in microbial diversity among tick life stages and sexes, with lowest microbial alpha diversity observed in adult females. No associations between tick genetic diversity and bacterial diversity were observed. Our study demonstrates systematic changes in tick bacterial microbiota diversity along elevational gradients. The observed patterns mirror diversity changes along elevational gradients typically observed in macroscopic taxa, and they highlight the key role of environmental factors in shaping within-host microbial communities in ectotherms.

Healthcare Providers' Perceptions of Challenges with Frequent Users of Emergency Department Care in Switzerland: A Qualitative Study.

Frequent users of emergency departments (FUED; ≥ 5 ED visits/year) commonly cumulate medical, social, and substance use problems requiring complex and sustained care coordination often unavailable in ED. This study aimed to explore ED healthcare providers' challenges related to FUED care to gain insight into the support and resources required to address FUED complex needs. An online survey was sent to all general adult emergency services within Switzerland (N = 106). Participants were asked to indicate the extent to which they perceived that FUED represented a problem and to describe the main challenges encountered. In total, 208 physicians and nurses from 75 EDs (70.7%) completed the survey. Among the 208 participants, 134 (64%) reported that FUED represented a challenge and 133 described 1 to 5 challenges encountered. A conventional content analysis yielded 4 main categories of perceived challenges. Negative consequences in the ED secondary to FUED's presence (eg, ED overcrowding, staff helplessness, and fatigue) was the most frequently reported challenge, followed by challenges related to FUEDs' characteristics (eg, mental health and social problems) leading to healthcare complexity. The third most frequently encountered challenge was related to the ED inappropriateness and inefficiency to address FUEDs' needs. Finally, challenges related to the lack of FUED healthcare network were the least often mentioned. ED healthcare providers experience a wide range of challenges related to FUED care. These findings suggest that currently EDs nor their staff are equipped to address FUEDs' complex needs.

Health care providers' perception of the frequent emergency department user issue and of targeted case management interventions: a cross-sectional national survey in Switzerland.

BACKGROUND: Frequent users of emergency departments (FUEDs) (≥5 ED visits/year) represent a vulnerable population with complex needs accounting for a significant number of emergency department (ED) consultations, thus contributing to EDs overcrowding. Research exploring ED staff perceptions of FUEDs is scarce. OBJECTIVES: The current study aimed to evaluate in ED staff a) the extent to which FUEDs are perceived as an issue; b) their perceived levels of knowledge and understanding of FUEDs; c) levels of perceived usefulness of case management (CM) and interest in implementing this intervention in their ED service. METHODS: Head physicians of the EDs at all public hospitals in Switzerland (of various level of specialization) were sent a 19-item web-based survey, pilot tested prior to its dissemination. The head physicians were asked to forward the survey to ED staff members from different health professional backgrounds. RESULTS: The hospital response rate was 81% (85/106). The exploitable hospital response rate was 71% (75/106 hospitals) including 208 responding health professionals. Issues and difficulties around FUEDs were perceived as important by 64% of respondents. The perceived frequency of being confronted with FUEDs was higher among nurses in more specialized EDs. In total, 64% of respondents felt poorly informed about FUEDs, nurses feeling less informed than physicians. The understanding of FUEDs was lower in the French-Italian-speaking parts (FISP) of Switzerland than in the German-speaking part. Eighty-one percent of respondents had no precise knowledge of FUED-related interventions. The perceived usefulness of CM interventions after receiving explanations about it was high (92%). However, the overall level of interest for CM implementation was 59%. The interest in CM by physicians was low across all regions and ED categories. Nurses, on the other hand, showed more interest, especially those in EDs of high specialization. CONCLUSIONS: The majority of ED staff reported being confronted with FUEDs on a regular basis. Staff perceived FUEDs as a vulnerable population, yet, they felt poorly informed about how to manage the issue. The majority of ED staff thought a CM intervention would be useful for FUEDs, however there appears to be a gap in their desire or willingness to implement such interventions.

Multiple trajectories of alcohol use and the development of alcohol use disorder: Do Swiss men mature-out of problematic alcohol use during emerging adulthood?

(A) OBJECTIVE: This study aimed to identify trajectories of alcohol use (AU) and their associations with the development of alcohol use disorder (AUD) among young men with different weekly drinking patterns. (B) METHOD: A longitudinal latent class analysis integrating several aspects of AU, such as drinking quantity and frequency on weekends vs workweek days, involving 4719 young Swiss men at ages 20, 21, and 25, and collected by the Cohort Study on Substance Use Risk Factors, was used to identify different AU trajectories over time. The development of AUD scores in these trajectories was investigated using generalized linear mixed models. (C) RESULTS: Six AU trajectory classes, similar to those described in the literature, were identified: 'abstainers-light drinkers', 'light workweek increasers', 'light decreasers', 'moderate weekend decreasers', 'moderate workweek increasers', and 'heavy drinkers'. Only 12% of participants were assigned to a trajectory class with decreasing AU associated with a decline in their AUD score. AUD scores increased in trajectory classes exhibiting increasing AU on workweek days, despite low and moderate general AU. Finally, more than 59% of participants were on an AU trajectory presenting no change in their mean AUD score over time. (D) CONCLUSIONS: Maturing out of problematic AU in emerging adulthood is not the norm in Switzerland, and the AUD score developed in late adolescence remains until at least emerging adulthood. AU on workweek days is a more practical marker of potentially problematic AU. This calls for timely interventions in adolescence and concerning regular drinking on workweek days in emerging adulthood.

Reconsidering the associations between self-reported alcohol use disorder and mental health problems in the light of co-occurring addictions in young Swiss men.

BACKGROUND: Alcohol use disorder (AUD) is known to co-occur with other addictions, as well as with mental health problems. However, the effects of other addictions co-occurring with AUD on mental health problems were rarely studied and not considering them may bias estimates of the association between AUD and mental health problems. This study investigated which role co-occurring addictions play for the cross-sectional associations between self-reported AUD and mental health problems. METHOD: Participants were 5516 young Swiss men (73.0% of those that gave written informed consent) who completed a self-report questionnaire. Using short screening questionnaires, we assessed three substance use disorders (alcohol, cannabis and tobacco), seven behavioural addictions (internet, gaming, smartphone, internet sex, gambling, work, exercise) and four mental health problems (major depression, bipolar disorder, attention deficit hyperactivity disorder (ADHD) and social anxiety disorder). Differences in the proportions of mental health problems were tested using logistic regressions between (1) participants with no AUD and AUD, (2) participants with no AUD and AUD alone and (3) participants with no AUD and AUD plus at least one co-occurring addiction. RESULTS: Overall, (1) participants with AUD had higher proportions of major depression (Odds ratio (OR [95% confidence interval]) = 3.51 [2.73, 4.52]; ADHD (OR = 3.12 [2.41, 4.03]); bipolar disorder (OR = 4.94 [3.38, 7.21]) and social anxiety (OR = 2.21 [1.79, 2.73])) compared to participants with no AUD. Considering only participants with AUD alone compared to participants with no AUD (2), differences in proportions were no longer significant for major depression (OR = 0.83 [0.42, 1.64]), bipolar disorder (OR = 1.69 [0.67, 4.22]), social anxiety (OR = 1.15 [0.77, 1.73]) and ADHD (OR = 1.65 [1.00, 2.72]) compared to participants with no AUD. In contrast, (3) proportions of mental health problems were considerably higher for participants with AUD plus at least one other addiction when compared to participants with no AUD, with OR's ranging from 2.90 [2.27, 3.70] for social anxiety, 4.03 [3.02, 5.38] for ADHD, 5.29 [4.02, 6.97] for major depression to 6.64 [4.44, 9.94] for bipolar disorder. CONCLUSIONS: AUD was associated with all four measured mental health problems. However, these associations were mainly due to the high proportions of these mental health problems in participants with AUD plus at least one co-occurring addiction and only to a lesser degree due to participants with AUD alone (i.e. without any other co-occurring addictions). Hence, estimates of the association between AUD and mental health problems that do not consider other addictions may be biased (i.e. overestimated). These findings imply that considering addictions co-occurring with AUD, including behavioural addictions, is important when investigating associations between AUD and mental health problems, and for the treatment of AUD and co-morbid disorders.

Protective Behavioral Strategies Scale-20: Psychometric properties of a French and German version among young males in Switzerland.

OBJECTIVE: The Protective Behavioral Strategies Scale (PBSS-20) is one of the most commonly used measures of engagement in protective behavioral strategies (PBS). This research aimed to examine the psychometric properties of a French and German version of the PBSS-20 in a large sample of young males in Switzerland. METHOD: The sample included 5,017 young males (mean age = 25.44) participating in the Cohort Study on Substance Use Risk Factors in Switzerland. Measures of PBS use, total drinks per week, and alcohol-related consequences were used from a second follow-up assessment. RESULTS: Confirmatory factor analysis testing different models previously documented in the literature provided initial support for a four-factor model. Fit statistics indicated that this model adequately reflects the structure of data. Further findings also provided support for adequate internal consistency and for convergent validity of this four-factor model, whereas metric-but not scalar-measurement invariance across linguistic regions was demonstrated. CONCLUSION: Although further research testing measurement invariance across linguistic regions and gender is warranted, results of the current study suggest that the French and German PBSS-20 is reliable and that it may represent a promising research and clinical tool that can be used in both French- and German-speaking countries.

Small-scale spatial variation in infection risk shapes the evolution of a Borrelia resistance gene in wild rodents.

Spatial variation in pathogen-mediated selection is predicted to influence the evolutionary trajectory of host populations and lead to spatial variation in their immunogenetic composition. However, to date few studies have been able to directly link small-scale spatial variation in infection risk to host immune gene evolution in natural, nonhuman populations. Here, we use a natural rodent-Borrelia system to test for associations between landscape-level spatial variation in Borrelia infection risk along replicated elevational gradients in the Swiss Alps and Toll-like receptor 2 (TLR2) evolution, a candidate gene for Borrelia resistance, across bank vole (Myodes glareolus) populations. We found that Borrelia infection risk (i.e., the product of Borrelia prevalence in questing ticks and the average tick load of voles at a sampling site) was spatially variable and significantly negatively associated with elevation. Across sampling sites, Borrelia prevalence in bank voles was significantly positively associated with Borrelia infection risk along the elevational clines. We observed a significant association between naturally occurring TLR2 polymorphisms in hosts and their Borrelia infection status. The TLR2 variant associated with a reduced likelihood of Borrelia infection was most common in rodent populations at lower elevations that face a high Borrelia infection risk, and its frequency changed in accordance with the change in Borrelia infection risk along the elevational clines. These results suggest that small-scale spatial variation in parasite-mediated selection affects the immunogenetic composition of natural host populations, providing a striking example that the microbial environment shapes the evolution of the host's immune system in the wild.

Non-medical use of prescription drugs by young men: impact of potentially traumatic events and of social-environmental stressors.

Background: Non-medical use of prescription drugs (NMUPD) is an increasing phenomenon associated with physical and psychological consequences. This study investigated the effects of distinct forms of stress on NMUPD. Methods: Data from 5308 young adult men from the Swiss cohort study on substance use risk factors (C-SURF) were analysed regarding NMUPD of sleeping pills, tranquilizers, opioid analgesics, psychostimulants, and antidepressants. Various forms of stress (discrete, potentially traumatic events, recent and long-lasting social-environmental stressors) during the period preceding the NMUPD assessment were measured. Backward log-binomial regression was performed and risk ratios (RR) were calculated. Results: NMUPD was significantly associated with the cumulative number of potentially traumatic events (e.g. for opioid analgesics, RR = 1.92, p < .001), with problems within the family (e.g. for sleeping pills, RR = 2.45, p < .001), and the peer group (e.g. for tranquilizer use, RR = 2.34, p < .01). Factors describing family functioning in childhood showed very few significant associations. Sexual assault by acquaintances was associated only with use of sleeping pills (RR = 2.91, p p <.01); physical assault by acquaintances was not associated with NMUPD. Physical (e.g. for psychostimulants, RR = 2.01, p < .001) or sexual assaults (e.g. for antidepressants, RR = 4.64, p < .001) perpetrated outside the family context did show associations with several drug categories. Conclusion: NMUPD appears to be more consistently associated with discrete and potentially traumatic events and with recent social-environmental stressors than with long-lasting stressors due to family functioning during childhood and youth. Physical and sexual assaults perpetrated by strangers showed more associations with NMUPD than those perpetrated by a family member.

Introducción: El uso no médico de fármacos recetados (UNMFR) es un fenómeno creciente asociado con consecuencias físicas y psicológicas. Este estudio investigó los efectos de distintas formas de estrés en el UNMFR.Métodos: Se analizaron los datos de 5,308 varones adultos jóvenes del estudio suizo de cohorte sobre los factores de riesgo del uso de sustancias (C-SURF) con respecto a UNMFR de pastillas para dormir, tranquilizantes, analgésicos opioides, psicoestimulantes y antidepresivos. Se midieron diversas formas de estrés (eventos discretos potencialmente traumáticos, estresores socioambientales recientes y duraderos) durante el período anterior a la evaluación del UNMFR. Se realizó una regresión logística- binaria hacia atrás y se calculó el riesgo relativo (RR).Resultados: UNMFR se asoció significativamente con el número acumulativo de eventos potencialmente traumáticos (e.g. para analgésicos opioides, RR = 1.92, p <.001), con problemas dentro de la familia (e.g. para pastillas para dormir RR = 2.45, p <.001). y el grupo de iguales (e.g. para el uso de tranquilizantes RR = 2.34, p <.01). Los factores que describen el funcionamiento familiar en la infancia mostraron escasas relaciones significativas. La agresión sexual por conocidos solo se asoció con el uso de pastillas para dormir (RR = 2.91, p = <. 01) mientras que la agresión física por conocidos no se asoció con UNMFR. La actividad física (e.g. para psicoestimulantes RR = 2.01, p <.001) o agresiones sexuales (e.g, para antidepresivos RR = 4.64, p <.001) perpretados fuera del contexto familiar mostraron asociaciones con varias categorías de fármacos.Conclusión: El UNMFR parece asociarse de forma más consistente con eventos discretos y potencialmente traumáticos y con estresores sociales y ambientales recientes que con factores estresantes de larga duración debidos al funcionamiento familiar durante la infancia y la juventud. Las agresiones físicas y sexuales perpetradas por extraños mostraron más asociaciones con el UNMFR que las cometidas por un miembro de la familia.

Temporal scale dependent interactions between multiple environmental disturbances in microcosm ecosystems.

Global environmental change has negative impacts on ecological systems, impacting the stable provision of functions, goods, and services. Whereas effects of individual environmental changes (e.g. temperature change or change in resource availability) are reasonably well understood, we lack information about if and how multiple changes interact. We examined interactions among four types of environmental disturbance (temperature, nutrient ratio, carbon enrichment, and light) in a fully factorial design using a microbial aquatic ecosystem and observed responses of dissolved oxygen saturation at three temporal scales (resistance, resilience, and return time). We tested whether multiple disturbances combine in a dominant, additive, or interactive fashion, and compared the predictability of dissolved oxygen across scales. Carbon enrichment and shading reduced oxygen concentration in the short term (i.e. resistance); although no other effects or interactions were statistically significant, resistance decreased as the number of disturbances increased. In the medium term, only enrichment accelerated recovery, but none of the other effects (including interactions) were significant. In the long term, enrichment and shading lengthened return times, and we found significant two-way synergistic interactions between disturbances. The best performing model (dominant, additive, or interactive) depended on the temporal scale of response. In the short term (i.e. for resistance), the dominance model predicted resistance of dissolved oxygen best, due to a large effect of carbon enrichment, whereas none of the models could predict the medium term (i.e. resilience). The long-term response was best predicted by models including interactions among disturbances. Our results indicate the importance of accounting for the temporal scale of responses when researching the effects of environmental disturbances on ecosystems.

Ectoparasite reproductive performance when host condition varies.

Host condition can influence both the nutritive resources available to parasites and the strength of host defences. Since these factors are likely to be correlated, it is unclear whether parasites would be more successful on hosts in good, intermediate or poor conditions. For more complex parasites, like fleas, where larvae depend on adults to extract and make available some essential host resources, host condition can act at two levels. First, it can affect the investment of females into eggs, and second, it can influence offspring growth. In a two-step experiment, we first let female hen fleas Ceratophyllus gallinae feed on nestlings of reduced, control or enlarged great tit Parus major broods and secondly used the blood from these nestlings as a food source for flea larvae reared in the laboratory. We then assessed the effect of brood size manipulation on reproductive investment and survival of female fleas, and on survival, developmental time, mass and size of pre-imago larvae and adults of the first generation. Although host condition, measured as body mass controlled for body size, was significantly influenced by brood size manipulation, it did not affect the female fleas' reproductive investment and survival. Larvae fed with blood from nestlings of reduced broods lived longer, however, than larvae fed on blood from enlarged or control broods. Additionally, F1 adults grew shorter tibiae when their mother had fed on hosts of reduced broods. The finding that brood size manipulation influenced parasite reproduction suggests that it affected nutritive resources and/or host defence, but the precise mechanism or balance between the two requires further investigation.

On the equivalence of host local adaptation and parasite maladaptation: an experimental test.

In spatiotemporally varying environments, host-parasite coevolution may lead to either host or parasite local adaptation. Using reciprocal infestations over 11 pairs of plots, we tested local adaptation in the hen flea and its main host, the great tit. Flea reproductive success (number of adults at host fledging) was lower on host individuals from the same plot compared with foreign hosts (from another plot), revealing flea local maladaptation. Host reproductive success (number of fledged young) for nests infested by foreign fleas was lower compared with the reproductive success of controls, with an intermediate success for nests infested by local fleas. This suggests host local adaptation although the absence of local adaptation could not be excluded. However, fledglings were heavier and larger when reared with foreign fleas than when reared with local fleas, which could also indicate host local maladaptation if the fitness gain in offspring size offsets the potential cost in offspring number. Our results therefore challenge the traditional view that parasite local maladaptation is equivalent to host local adaptation. The differences in fledgling morphology between nests infested with local fleas and those with foreign fleas suggest that flea origin affects host resource allocation strategy between nestling growth and defense against parasites. Therefore, determining the mechanisms that underlie these local adaptation patterns requires the identification of the relevant fitness measures and life-history trade-offs in both species.

Spatial distribution of soil contamination by Toxoplasma gondii in relation to cat defecation behaviour in an urban area.

In urban areas, there may be a high local risk of zoonosis due to high densities of stray cat populations. In this study, soil contamination by oocysts of Toxoplasma gondii was searched for, and its spatial distribution was analysed in relation to defecation behaviour of cats living in a high-density population present in one area of Lyon (France). Sixteen defecation sites were first identified. Cats were then repeatedly fed with marked food and the marked faeces were searched for in the defecation sites. Of 260 markers, 72 were recovered from 24 different cats. Defecation sites were frequented by up to 15 individuals. Soil samples were also examined in order to detect the presence of T. gondii using real-time PCR. The entire study area was then sampled according to cat density and vegetation cover type. Only three of 55 samples were positive and all came from defecation sites. In a second series of observations, 16 defecation sites were sampled. Eight of 62 samples tested positive, originating in five defecation sites. Laboratory experiments using experimental seeding of soil showed that the inoculated dose that can be detected in 50% of assays equals 100-1000oocysts/g, depending on the strain. This study shows that high concentrations of oocysts can be detected in soil samples using molecular methods and suggests that spatial distribution of contamination areas is highly heterogeneous. Positive samples were only found in some of the defecation sites, signifying that at-risk points for human and animal infection may be very localised.

Prevalence of Toxoplasma gondii in small mammals from the Ardennes region, France.

Serum samples from 218 small mammals trapped in forest and grassland in the Ardennes region (North-eastern France) were tested for antibodies to Toxoplasma gondii. Using the modified agglutination test, positive results were found in 4/92 Apodemus sp., 3/64 Clethrionomys glareolus, 0/26 Microtus agrestis, 0/4 Micromys minutus, 3/5 Sorex sp., 2/9 Arvicola terrestris, and 7/18 Talpa europaea. Toxoplasma gondii was not isolated from the heart of seropositive individuals after bioassay in mice. Seroprevalence was significantly higher in large fossorial mammals living in grassland than in small forest mammals, probably related to ecological factors.