Erkinis encefalitas (EE) yra dažniausia ir sunkiausia virusinė nervų sistemos infekcija, neturinti specifinio priešvirusinio gydymo. Vienintelė efektyvi šios ligos profilaktikos priemonė yra vakcinacija. Nesant galimybių įvesti visuotinę vakcinaciją nuo EE mūsų šalyje, ypač svarbu nustatyti didžiausią šios ligos riziką turinčias gyventojų grupes, kurioms būtų teikiamas vakcinacijos prioritetas. Pagal tarptautines Laimo boreliozės (LB) diagnostikos ir gydymo gaires, klinikiniai sindromai ir jų trukmė yra svarbiausias šios ligos diagnostikos kriterijus. Serologiniai tyrimai vaidina tiktai pagalbinį vaidmenį patvirtinant diagnozę. Pagrindinis serologinių tyrimų trūkumas yra tas, kad jie neleidžia atskirti aktyvios infekcijos nuo buvusio kontakto su šios ligos sukėlėjais. Laimo boreliozės atveju tai labai svarbu, kadangi endeminiuose rajonuose nuo 1,8 iki 26 proc. sveikų žmonių turi šios ligos sukėlėjų antikūnus dėl buvusios besimptomės infekcijos praeityje. Neįmanoma teisingai interpretuoti LB serologinių tyrimų, nežinant LB paplitimo regione, kuriame šie tyrimai taikomi LB diagnostikai. Šis darbas yra pirmasis Lietuvoje LB sukėlėjų antikūnų paplitimo tyrimas, kuriame nustatytas dviejų pagrindinių erkių pernešamų ligų sukėlėjų antikūnų serokonversijos dažnis tyrimo laikotarpiu, didelio endemiškumo regione, tiriamųjų imtį sudarius atsitiktinės sluoksniuotos atrankos pagal amžių ir lytį principu. Šiame darbe ištirtos įvairių rizikos veiksnių sąsąjos su EE ir LB sukėlėjų paplitimu... [toliau žr. visą tekstą] / TBE is the most common and severe CNS affecting zoonosis. No specific treatment for TBE exists. Tick-borne encephalitis can be prevented by active immunization. Due to governmental financial shortages this vaccination is not included in the national program of imunoprophylaxis for the years 2014-2018. It is very important to find out groups for priority vaccination according to living area, age, leisure activities and occupational risk. Lyme borreliosis diagnosis should be based primarily on the clinical presentation and an assessment of tick exposure risk. In most cases laboratory diagnosis is only supporting clinical picture. Antibody assays still fall short of being completely sensitive and specific to distinguish acute and chronic infection. The diagnostic specificity of serum antibody tests is low because seropositivity in normal population ranges from 1.8% to 26% and LB IgM and IgG may persist for years. The interpretation of serological tests may also lead to misdiagnosis not knowing the seroprevalence of LB in the area. This is the first study of seroprevalence of LB and incidence of TBE and LB during a three year period in Lithuania. The study was conducted in high endemic areas and random samples stratified by gender and age groups were made. Only a few studies perform neutralization tests for detecting TBEV antibodies. Assumed risk factors for the prevalence of TBE and LB were established.

Borrelia afzelii differential gene expression in the course of tick blood-feeding, and during chronic infection in mice was studied. Temperature effect on B. afzelii gene expression and infectivity was investigated. Infection rates of mice immunized with B. afzelii tick gut antigen at various stages of tick blood-intake were analyzed. This work was funded by the Grant Agency of the Czech Republic, Project No. 17-27393S to Radek Šíma.

I describe procedures for the introduction of Borrelia burgdorferi, the spirochetal agent of Lyme disease, into larval and nymphal stage of the tick vector, Ixodes ricinus. The goal of this Mgr. Thesis is to find an optima system, that would reliably and reproducibly allow the infection of large numbers of ticks with the Lyme disease spirochete.

Les maladies à tiques posent un problème majeur que se soit du point de vue de la santé animale ou de la santé humaine. Parmi ces pathologies, la borréliose de Lyme est la maladie à transmission vectorielle la plus fréquente de l’Hémisphère Nord et, en France, l’Alsace représente l’une des régions avec la plus forte incidence. Ce travail de thèse a eu pour objectif d’évaluer les densités en nymphes ainsi que les taux d’infection à Borrelia burgdorferi sl et Anaplasma phagocytophilum dans cette région. Nous avons comparé nos résultats à ceux établis dans cette même région en 2003 et 2004. De plus nous avons étudié les facteurs environnementaux potentiellement responsables de la variabilité inter-site de la densité en nymphes et également cartographié le risque de borréliose de Lyme en Alsace. Notre travail, qui pour l’instant a été conduit en Alsace, tend à s’étendre à d’autres régions de France. Il nous paraît pertinent de poursuivre les études de terrains sur certains sites pris en compte dans ce travail de façon à objectiver les tendances observées dans notre région. / Vector-borne diseases are today a major threat for human and animal health. Among those diseases, Lyme borreliosis is the most frequent vector-borne disease occurring in the Northern hemisphere, and the numbers of humans affected have been increasing in some parts of the world. In France, Lyme borreliosis is endemic to several regions including the Alsace region.The aim of this work was to investigate nymph densities and infection prevalence of Borrelia burgdoferi sl and Anaplasma phagocytophilum in this region. We compared our results to those obtained by Ferquel et al. in 2003 and 2004. We studied environmental factors involved in inter-site nymph density variability and mapped Lyme borreliosis nymph density in Alsace.For instance our work that has been conducted in Alsace, is now extended in other region of France. It will be interesting to validate our results with data from other area.

Laimo boreliozė (LB) yra labiausiai paplitusi erkių platinama liga. Ligos sukėlėjus perneša Ixodes rūšies erkės. Didelį borelijų paplitimą lemia platus rezervuarinių šeimininkų ratas. Šį susirgimą gali sukelti kelios B. burgdorferi s. l. komplekso bakterijų rūšys: B. afzelii, B. garinii, B. burgdorferi sensu stricto. Šiame darbe buvo tirtos 134 Ixodes ricinus erkės nuo 8 elninių gyvūnų (4 stirnų ir 4 elnių) ir 73 erkės nuo žolės (elninių teritorijoje). Naudojant dauginės polimerazės grandininės reakcijos (PGR) medodą, 9 - iose (4,3%) iš jų buvo nustatytas užsikrėtimas Borrelia burgdorferi s. l. patogenais, septyniuose mėginiuose buvo identifikuota B. afzelii, viename - B. garinii rūšis. Viename mėginyje buvo nustatyta Borrelia spp., kuri nebuvo identifikuota. Atlikta B. burgdorferi s. l. sekų analizė pagal ospA geną, naudojantis genų banko duomenimis, atskleidė polimorfizmo lygį tarp trijų, žmogui patogeniškų Borrelia rūšių ir parodė padermių pasiskirstymą skirtingose šalyse bei šeimininkuose. Variabiliausios nustatytos B. garinii ospA geno sekos, rasta 361 variabili vieta (nukleotidų įvairovė π=0,072), aptikta 18 sekų variantų. Mažesnis variabilumas nustatytas B. burgdorferi s. s. sekose – aptiktos 266 variabilios vietos (nukleotidų įvairovė π=0,16) ir 12 sekų variantų bei B. afzelii sekose – aptiktos 257 variabilios vietos (nukleotidų įvairovė π=0,17) ir 4 sekų variantai. Didesni skirtumai buvo identifikuoti tarp B. afzelii ospA geno sekų (vidutinis genetinis atstumas... [toliau žr. visą tekstą] / Lyme borreliosis (LB) is the most common tick - born disease. The pathogens are transmitted by infected ticks belonging to a species of the genus Ixodes. The high prevalence of Borrelia is determined by a wide circle of reservoir hosts. The disease can be caused by a few bacterial species of B. burgdorferi s.l. complex, such as: B. afzelii, B. garinii and B. burgdorferi sensu stricto. 134 Ixodes ricinus ticks have been explored in the thesis, collected from 8 certine animals (4 roe deer and 4 deer) and 73 ticks collected from grass (in the territory of certine animals). Using multiplex polymerase chain reaction (PCR) method, the infection with Borrelia burgdorferi s. l. pathogens was identified in 9 (4.3%), B. afzelii was identified in seven samples, while B. garinii species was found in one of them. Borrelia spp. was found in one sample, which has not been identified. A sequence analysis B. burgdorferi s. l. implemented according to the ospA gene by using a gene bank data revealed level of polymorphism among three Borrelia species pathogenic to human and showed the distribution of strains in the different countries and hosts. The most variable gene sequences are B. garinii ospA. It is found 361 variable place (nucleotide diversity π=0,072), ant detected 18 sequence variants. Less variability found in B. burgdorferi s. s. sequences: 266 variable places are found and 12 sequence variants (nucleotide diversity π=0,16) and 257 variable places are discovered in B. afzelii... [to full text]

Lyme borreliosis is a tick-transmitted infectious disease. The causative agents are spiral-shaped bacteria and the most common sign of infection is a skin rash at the site of the tick bite. If not treated with antibiotics, the bacteria can disseminate and cause a variety of different manifestations including arthritis, carditis or neurological problems. The disease is a zoonosis and the bacteria are maintained in nature by different vertebrate reservoir host animals. In Europe, three different Borrelia genospecies cause Lyme borreliosis: B. burgdorferi, B. afzelii and B. garinii. The latter depends in part on birds as its reservoir host. B. garinii bacteria have been found in a marine enzootic infection cycle worldwide and also among terrestrial birds. This thesis suggests that passerine birds and seabirds constitute an important reservoir for B. garinii bacteria also with clinical importance. We have found bacteria very similar to Lyme borreliosis causing isolates in ticks infesting migrating passerine birds. The birds not only transport infected ticks, but are competent reservoir hosts, as measured by their ability to infect naïve ticks. Their role as a reservoir host is dependent on their foraging behavior, where ground-dwelling birds are of greater importance than other species. When comparing B. garinii isolates from Europe, the Arctic and North Pacific, and including isolates from seabirds, passerine birds, Ixodes ricinus ticks and Lyme borreliosis patients, we found that phylogenetic grouping was not necessarily dependent on geographical or biological origin. B. garinii from seabirds were very heterogeneous and found in all different groups. Therefore, the marine and the terrestrial infection cycles are likely to overlap. This was supported by the fact that B. garinii isolated from seabirds can establish a long-term infection in mice. Bacteria from the genospecies B. garinii are overrepresented among neuroborreliosis patients. Interestingly, many clinical B. garinii isolates are sensitive to human serum and have shown weak binding to the complement inhibitor protein factor H. By transforming a serum-sensitive B. garinii isolate with a shuttle vector containing the gene for the factor H binding protein OspE from complement-resistant B. burgdorferi, serum resistance could be increased. In addition, neurovirulent B. garinii strains recently isolated from neuroborreliosis patients were shown to express a factor H binding protein, not found in bacteria that had been kept in culture for a long time. This protein may contribute to the virulence of neuroborreliosis-causing B. garinii strains. When testing B. garinii isolates from Lyme borreliosis patients and seabirds for resistance to human serum, all members of the latter group were sensitive to even low levels of serum. This suggests that seabird isolates are not capable of infecting humans. In agreement with this, B. garinii isolated from seabirds do not appear to bind human factor H.

Tick-borne diseases are caused by a group of pathogenic microorganisms which are transmitted between animal and human population by vector which is most frequently tick. Evaluation of danger and perils of these diseases is important due to prevention and monitoring of current situation development. The most common tick-borne diseases in the Czech Republic are borreliosis, tick-borne encephalitis and ehrlichiosis. Rarely can we encounter bartonellosis, babesiosis, rickettsiosis and tularemia. All these diseases can have serious consequences and in critical cases they can result in death of the infected person. One of the basic and the most important of preventive measures which lower the risk of the infection by any tick-borne disease is prevention of tick encounter and eventually vaccination. Due to continual global warming we can expect that in near future ticks will spread even to locations which have been so far not suitable for their development. We can expect that we will even more frequently encounter tick-borne diseases - including diseases which were formerly not found in our territory or were very rare. As a part of health education it will be needed more to get known basic information of tick-borne diseases and their prevention. Different educational centres are an ideal place for...

La réduction de l’exposition aux tiques est la méthode la plus efficace de prévention de la borréliose de Lyme, maladie qui pose une nouvelle problématique de santé publique dans les espaces périurbains. Ainsi, la mise en évidence de contacts entre les itinéraires de déplacement des usagers en forêt et les habitats favorables aux populations de tiques constitue une voie privilégiée. L’intérêt est de spatialiser ce contact et de réfléchir à minimiser le risque sur le plan paysager. Pour étudier ce contact, deux bases de données ont été constituées, l’une relative aux tiques susceptibles de transmettre l’infection, l’autre aux itinéraires des usagers en forêt de Sénart (Île-de-France). La première est alimentée par des échantillons de tiques collectées sur la végétation en forêt et la seconde rassemble des données descriptives sur les pratiques et les comportements de déplacement des usagers dans l’espace forestier. Une caractérisation des secteurs les plus fréquentés en lien avec la distribution des populations de tiques nous a permis d’évaluer l’exposition en fonction des lieux visités. La sphère des représentations et des idées a également été explorée afin de comprendre les mécanismes de la rencontre avec une tique. En intégrant ces résultats dans un outil de géosimulation multi-agent, diverses actions relatives à l’aménagement forestier pourront être discutées avec les gestionnaires forestiers telles que, par exemple, la mise en défens de certaines zones à certaines périodes de l’année, le déplacement ou la fermeture de certains sentiers, ou encore la modification des points d’attractions des usagers dans la forêt. / Reducing exposure to ticks is the most effective method for prevention of Lyme borreliosis, which poses a new public health problem in periurban areas. Therefore, the analysis of contacts between the routes that people adopt in forests (where ticks live) and the spaces and environments considered to be risky (the most suitable habitat for ticks) constitutes a privileged avenue of study. So there is a need to study these spatial dynamics, as well as to study ways in which it is possible to minimize risk via the landscape and design. To study this contact, two databases were created, one related to ticks that can transmit the infection and the other to trajectories of users in the Sénart forest (Île-de-France). The first was fed by tick samples collected from vegetation in the forest and the second gathered descriptive data on volume, variation and characteristics of human flow through the forest area. A characterization of the busiest portions of routes in relation to data on tick populations densities and distribution has enable us to assess human exposure to ticks according to the forest locations attended by users. We also explored the realm of representations and ideas in order to understand the mechanisms of human-tick contact. By integrating these results into a multi-agent geosimulation tool, various actions related to forest design will be discussed with the forest officers such as, for example, the closing off of certain areas at certain times of the year, the relocation or closure of some trails, or the changing of points of attractions for users in the forest.

The aim of this work is to point out the interconnectedness of human life with parasitic organisms, especially with the Castor bean tick (Ixodes ricinus). This tick forms an integral part of our rich invertebrate fauna and has become an increasingly frequent interest of media in the last few decades. This thesis attempts to bring closer the relationship between tick and man from different perspectives, and to reveal essence as well as pitfalls of tick life. For many people, this arthropod represents an insurmountable resource of aversion and fear. Hence, an integral part of the thesis is the introduction of prevention methods and treatment of parasitic diseases transmitted by the tick, as well as monitoring of new trends in the therapy and development of vaccines. Also, the text offers a proposal how to bring the tick closer to the pupils in teaching Biology. KEYWORDS The Castor bean tick, parasite-host relationship, life cycle, encephalitis, borreliosis, collection methods

La variation de la diversité des communautés d’hôtes réservoirs peut modifier le risque de maladies impliquant ces espèces. En particulier, l’introduction d’une espèce potentiellement réservoir est susceptible d’augmenter le risque de maladie, en agissant comme un réservoir supplémentaire et/ou en amplifiant la circulation des agents pathogènes chez les réservoirs autochtones. L’objectif du travail de thèse est de quantifier la contribution, d’une espèce introduite, le tamia de Sibérie (Tamias sibiricus barberi), au risque d’une maladie multi-hôtes, la borréliose de Lyme, due à des bactéries appartenant au complexe d’espèces Borrelia burgdorferi sensu lato et transmises par des tiques, principalement Ixodes ricinus en Europe. Dans un premier temps, nous avons testé si le tamia est un réservoir compétent pour la maladie de Lyme en milieu naturel, c'est-à-dire s’il est capable de transmettre B. burgdorferi sl aux tiques I. ricinus et de maintenir l’infection. Le tamia est fortement infesté par les tiques et infecté par les bactéries et il peut transmettre B. burgdorferi sl aux tiques. Nos résultats ne montrent pas clairement que le tamia peut maintenir l’infection. Une des deux composantes du risque de la maladie de Lyme pour l’homme est le risque acarologique, c'est-à-dire la densité de nymphes infectées en quête d’hôtes. Dans un deuxième temps, nous avons calculé la contribution du tamia au risque acarologique et l’avons comparé à celles du campagnol roussâtre (Myodes glareolus) et du mulot sylvestre (Apodemus sylvaticus), réservoirs avérés de B. burgdorferi sl. Puis, nous avons étudié la variation temporelle de la contribution du tamia et testé si sa présence influençait la contribution des réservoirs rongeurs natifs. Pour calculer la contribution au risque, nous avons utilisé deux approches, l’une basée sur des captures des rongeurs, et l’autre sur l’identification des espèces hôtes sur lesquelles se sont gorgées les tiques. Le tamia produit plus de nymphes infectées à l’affût que le campagnol et le mulot. La contribution du tamia varie entre années suivant la densité de tamias et intra-années suivant la disponibilité en tiques. Sa plus forte infestation par I. ricinus et infection par B. burgdorferi sl, que les rongeurs natifs, peuvent être expliquées par sa plus forte exposition aux tiques. En conclusion, le tamia semble un réservoir compétent pour B. burgdorferi sl, avec une forte contribution au risque acarologique et une amplification possible de la circulation des pathogènes dans les communautés natives. Sa présence peut augmenter le risque pour la borréliose de Lyme chez l’homme en augmentant la prévalence d’infection des nymphes, mais pas les densités de nymphes à l’affût. / The variation of the composition of host communities can modify the risk of diseases involving these species. In particular, the introduction of a potentially reservoir species may increase the disease risk, by acting as an additional reservoir or by amplifying the circulation of pathogens in the native reservoirs. We quantified the contribution of an introduced species, the Siberian chipmunk (Tamias sibiricus barberi), to the risk of a multi-host vector-borne disease, Lyme borreliosis (LB), due to bacteria that belong to the Borrelia burgdorferi sensu lato complex and transmitted by bites of hard ticks, especially by Ixodes ricinus ticks in Europe. First, we verified if the Siberian chipmunk is a competent reservoir host for LB in the field, by testing if chipmunks can transmit B. burgdorferi sl to I. ricinus ticks and maintain the infection. Chipmunks were highly infested by ticks and infected by B. burgdorferi sl, and they are able to transmit the bacteria to ticks. Our results did not show clear maintenance patterns. Second, one of the parameter of LB risk for human is the acarologic risk, which is the density of infected questing nymphs. We evaluated the contribution of chipmunks to this risk and compared it with the one of bank voles (Myodes glareolus) and wood mice (Apodemus sylvaticus), two known reservoir rodents. Moreover, we studied the variation of the contribution. We used two approaches, the one based on captures of rodents and the other one on host-blood meal analysis of questing nymphs. Chipmunks produced more infected nymphs than voles and mice. The contribution of chipmunks varies between years according to chipmunk density and during the year according to tick availability. The higher infestation by I. ricinus and infection by B. burgdorferi sl of chipmunks in comparison to native reservoir rodents, could be due to its higher exposition to ticks. As Siberian chipmunk seems to be a competent reservoir host for LB with strong contribution, they can “spillback” infection to native communities and increase the risk for LB to humans by increasing infection prevalence in nymphs, but not nymph density.