Sympatric Ixodes-tick species : pattern of distribution and pathogen transmission within wild rodent populations

The generalist tick Ixodes ricinus is the most important vector for tick-borne pathogens (TBP), including Borrelia burgdorferi sensu lato, in Europe. However, the involvement of other sympatric Ixodes ticks, such as the specialist vole tick I. trianguliceps, in the enzootic circulations of TBP remains unclear. We studied the distribution of I. ricinus and I. trianguliceps in Central Finland and estimated the TBP infection likelihood in the most common rodent host in relation with the abundance of the two tick species. Ixodes trianguliceps was encountered in all 16 study sites whereas I. ricinus was frequently observed only at a quarter of the study sites. The abundance of I. ricinus was positively associated with open water coverage and human population density around the study sites. Borrelia burgdorferi s. l.-infected rodents were found only in sites where I. ricinus was abundant, whereas the occurrence of other TBP was independent of I. ricinus presence. These results suggest that I. trianguliceps is not sufficient, at least alone, in maintaining the circulation of B. burgdorferi s. l. in wild hosts. In addition, anthropogenic factors might affect the distribution of I. ricinus ticks and, hence, their pathogens, thus shaping the landscape of tick-borne disease risk for humans.Peer reviewe

Masennuksen yhteys sydämen sykkeen tunnistamiseen ja sen vaikutus aivojen herätevasteisiin

Masennus on yksi suurimmista kansanterveyden ongelmista ja sillä onkin merkittävät inhimilliset ja taloudelliset vaikutukset. Masennus voi aiheuttaa monia psyykkisiä ja kehollisia oireita. Interoseptio tarkoittaa kykyä tunnistaa autonomisen hermoston signaaleja, kuten sydämen sykettä. Tämä kehoaisti saattaa osallistua siihen, miten kehon tuntemukset pystyvät vaikuttamaan mielen prosesseihin, esimerkiksi tunnekokemuksiin. Interoseptiivisella herkkyydellä ja sen muutoksilla näyttäisikin olevan yhteys moniin psykiatrisiin häiriöihin, myös masennukseen. Interoseptiiviset signaalit saavat aikaan mitattavia herätevasteita aivoissa. Näitä on tutkittu masentuneilla erittäin vähän. Tutkimuksessamme tarkastelimme sydämen sykkeen havainnointitehtävän avulla eroavatko masentuneet ja terveet verrokkihenkilöt interoseptiivisessä herkkyydessä. Osallistujat suorittivat sydämen syke- ja kuulohavainnon erottelutehtävän, jossa henkilön tuli tarkastella, oliko ääniärsyke synkroniassa sydämen sykkeen kanssa. Lisäksi tarkastelimme magnetoenkefalografialla (MEG), onko masentuneilla ja verrokeilla eroa interoseptio-tehtävän aikaisissa aivojen herätevasteissa temporaali- ja parietaalialueella sekä päälaen alueella. Ulkoisen ääniärsykkeen havainnointi toimi kontrollimittauksena. Masentuneiden ja verrokkien välillä ei havaittu eroja interoseptiivisessä herkkyydessä eikä interoseptio-tehtävän aikaissa aivojen herätevasteissa. Masentuneilla oli kuitenkin suuntaa-antavasti verrokkeja alhaisemmat herätevasteet kaikilla aivoalueilla riippumatta tarkkaavuuden suuntaamisesta. Tämä saattaisi antaa viitteitä siitä, että masentuneilla olisi yleisesti ottaen alhaisemmat sensorisen tiedon vasteet. Tulokset eivät kuitenkaan olleet merkitseviä eikä niiden perusteella voida tehdä liian suoria johtopäätöksiä. Tämä kuitenkin vahvistaa sitä, että tietoa tarvitaan yhä lisää masennuksen ja interoseption yhteydestä, sekä eksteroseption merkityksestä masennuksessa. Tämä voisi auttaa ymmärtämään paremmin masennuksen oireita sekä on tärkeää masennuksen hoitomuotojen kehittämisen kannalta.Major depressive disorder (MDD) is one of the largest public health problems. It has major human and economic impacts. MDD can lead to a variety of mental and physical symptoms. Interoception refers to the sense of internal bodily stimuli, for instance heartbeat. The body sense may partly explain how the current body state can influence mental processes, such as subjective feelings. Many psychiatric disorders, including MDD, are considered to be associated with interoceptive sensitivity and its abnormalities. Interoceptive signals cause measurable brain responses. These have been studied very little in depressed individuals. In this study, we examined interoceptive sensitivity in depressed individuals and healthy control volunteers using the heartbeat perception task. The participants had to discriminate whether the sound was synchronous with their heart tone. Furthermore, we studied using magnetoencephalography (MEG), whether depressed and control individuals differ in heartbeat-evoked brain potentials in temporal lobes, parietal lobes and vertex during the interoceptive task. Focusing attention on an auditory sound stimulus was used as a control condition. Depressed individuals did not differ significantly from the control group either in interoceptive sensitivity or heartbeat-evoked brain potentials. Depressed participants had, however, directionally lower brain responses than controls in all the brain areas regardless of the attentional focus. This could possibly refer to the generally lower level of sensory responses in depressed individuals. Nevertheless, the results were not significant and thus, has to be interpreted carefully. This confirms that more information is needed about interoception in depression and also the significance of exteroception in depression. It could help understand better the symptoms and would be important when developing treatment for MDD

Research data of article: "Sympatric Ixodes-tick species: pattern of distribution and pathogen transmission within wild rodent populations"

Longitudinal monitoring of bank voles as well as their ticks and tick-borne pathogens in Central Finland, carried out in 2012

Temporal dynamics of the tick Ixodes ricinus in northern Europe : epidemiological implications

Background Tick-borne pathogens pose an increasing threat to human and veterinary health across the northern hemisphere. While the seasonal activity of ticks is largely determined by climatic conditions, host-population dynamics are also likely to affect tick abundance. Consequently, abundance fluctuations of rodents in northern Europe are expected to be translated into tick dynamics, and can hence potentially affect the circulation of tick-borne pathogens. We quantified and explained the temporal dynamics of the tick Ixodes ricinus in the northernmost part of its European geographical range, by estimating (i) abundance in vegetation and (ii) infestation load in the most common rodent species in the study area, the bank vole Myodes glareolus. Results Ixodes ricinus nymphs and adult females, the life stages responsible for the most of tick bites in humans, peaked in May-June and August-September. Larvae and nymphs were simultaneously active in June and abundance of questing larvae and nymphs in the vegetation showed a positive association with bank vole abundance. Moreover, infesting larvae and nymphs were aggregated on bank voles, and the infestation of bank voles with I. ricinus larvae and nymphs was positively associated with bank vole abundance. Conclusion Our results indicate early summer and early autumn as periods of increased risk for humans to encounter I. ricinus ticks in boreal urban forests and suggest a 2 years life-cycle for I. ricinus with two cohorts of ticks during the same year. Moreover, we identified a simultaneous activity of larvae and nymphs which allows co-feeding on the rodent host, which in turn supports the transmission of several important zoonotic tick-borne pathogens. Finally, we showed that a high density of the rodent host may enhance the risk that ticks and, potentially, tick-borne pathogens pose to human health.peerReviewe