Incidence Of Tick-borne Encephalitis Research Articles

Potential drivers of human tick-borne encephalitis in the Örebro region of Sweden, 2010–2021

Incidence of tick-borne encephalitis (TBE) has increased during the last years in Scandinavia, but the underlying mechanism is not understood. TBE human case data reported between 2010 and 2021 were aggregated into postal codes within Örebro County, south-central Sweden, along with tick abundance and environmental data to analyse spatial patterns and identify drivers of TBE. We identified a substantial and continuing increase of TBE incidence in Örebro County during the study period. Spatial cluster analyses showed significant hotspots (higher number of cases than expected) in the southern and northern parts of Örebro County, whereas a cold spot (lower number of cases than expected) was found in the central part comprising Örebro municipality. Generalised linear models showed that the risk of acquiring TBE increased by 12.5% and 72.3% for every percent increase in relative humidity and proportion of wetland forest, respectively, whereas the risk decreased by 52.8% for every degree Celsius increase in annual temperature range. However, models had relatively low goodness of fit (R2 < 0.27). Results suggest that TBE in Örebro County is spatially clustered, however variables used in this study, i.e., climatic variables, forest cover, water, tick abundance, sheep as indicator species, alone do not explain this pattern.

Epidemiological Characteristics of Tick-Borne Encephalitis in the Sverdlovsk District over a 20-Year Period

Relevance. Despite the ongoing program of mass vaccination of tick-borne encephalitis (TBE) for more than 20 years in the Sverdlovsk district, the incidence rate of TBE continues to exceed the average in Russia and the Ural Federal region.Aim. To analyze the main indicators of the manifestation of the epidemic process of TBE in the territory of the Sverdlovsk district under the conditions of planned vaccination over a 20-year period (2002–2021).Materials and methods. The article uses data from federal and regional statistical observations, reporting materials of the Department of Rospotrebnadzor in the Sverdlovsk district for 2002-2021, methods of statistical analysis.Results and discussion. During the study period (2002-2021), 3861 cases of TBE were registered in the Sverdlovsk district, while the highest incidence rate was detected in 2005 – 10.1 per 100 thousand population, and the lowest in 2020 – 1.0 per 100 thousand population. The share of the vector-borne mechanism was 78.4%, the unidentified path – 20.1%, alimentary – 1.5%. Analysis of the seasonal distribution of cases of TBE showed that the incidence is recorded from April to November. Cases of TBE were recorded in all age groups, including the child population. Most often, people aged 60 years old and older (24.6%) were ill with TBE. Among the children's population, the largest share fell on children aged 7–14 years (5.4%). Men of working age prevailed among the patients (66.0%). TBE was mainly registered among the unvaccinated population (81.5%) with a predominance of urban (86.1%). Officials predominated among the sick persons – 29.8%, pensioners made up 22.3%, unemployed – 19.8%. Persons whose work is professionally connected with the forest made up only 0.6%. The ongoing program of mass vaccination of TBE has led to a decrease in the proportion of severe and moderate forms of diseases (focal – 9.8% and meningeal – 24.0%) and an increase in the proportion of febrile (33.8%) and atypical forms (32.4%). Deaths during the studied period were recorded mainly among the adult unvaccinated population.Conclusions. The Sverdlovsk district continues to be a tense natural focus of TBE with a constantly recorded incidence among contingents of different age and social groups. In the absence of highly effective etiotropic drugs for the treatment of TBE, the only strategy for reducing the incidence of TBE, the development of severe forms and deaths in the territory of the Sverdlovsk district is mass vaccination of the population.

The Effect of COVID‑19 on the Incidence of Human Vector-Borne Infections Transmitted by Ixodid Ticks (Illustrated by the Example of Krasnoyarsk Territory)

In 2022, there was an increase in the incidence of tick-borne encephalitis (TBE) and ixodid tick-borne borreliosis (ITBB) in the subjects of the Russian Federation, federal districts and the country as a whole. At the same time, among people affected by ixodid ticks, the proportion of clinical forms of the diseases has increased. The aim of this study is to analyze the possible causes of the simultaneous increase in the incidence of vector-borne infections and the proportion of clinical forms among the people bitten by the ticks, using the materials on Krasnoyarsk Territory as an example. Materials and methods. We analyzed the incidence of TBE and ITBB among the people who have or haven’t had COVID‑19, the number of people affected by tick bites in 2021–2022 in Krasnoyarsk Territory. Statistical analysis is performed by standard methods of variational statistics using Excel. Results and discussion. It is shown that in the Krasnoyarsk Territory, with a decrease in the number of individuals affected by tick bites in 2022 as compared to 2021 (12216 and 13214, respectively), there was an increase in the number of cases of TBE (from 124 to 250) and ITBB (from 115 to 224), as well as the proportion of people who had clinical forms of the infections after tick bites. Among three possible explanations of the observed pattern, a decrease in the immune status of Krasnoyarsk residents who had had COVID‑19 before the contact with ticks is considered as the most likely one. Using statistical methods it was substantiated that among people with TBE and ITBB, the proportion of individuals who have had COVID‑19 is significantly higher than expected, based on the actual incidence of the Krasnoyarsk Territory population with a new coronavirus infection. Thus, COVID‑19 affects the incidence of vector-borne infections indirectly, through a change in the number of people contacts with natural stations, and directly, by changing the immune status.

First Expert Elicitation of Knowledge on Possible Drivers of Observed Increasing Human Cases of Tick-Borne Encephalitis in Europe

Tick-borne encephalitis (TBE) is a viral disease endemic in Eurasia. The virus is mainly transmitted to humans via ticks and occasionally via the consumption of unpasteurized milk products. The European Centre for Disease Prevention and Control reported an increase in TBE incidence over the past years in Europe as well as the emergence of the disease in new areas. To better understand this phenomenon, we investigated the drivers of TBE emergence and increase in incidence in humans through an expert knowledge elicitation. We listed 59 possible drivers grouped in eight domains and elicited forty European experts to: (i) allocate a score per driver, (ii) weight this score within each domain, and (iii) weight the different domains and attribute an uncertainty level per domain. An overall weighted score per driver was calculated, and drivers with comparable scores were grouped into three terminal nodes using a regression tree analysis. The drivers with the highest scores were: (i) changes in human behavior/activities; (ii) changes in eating habits or consumer demand; (iii) changes in the landscape; (iv) influence of humidity on the survival and transmission of the pathogen; (v) difficulty to control reservoir(s) and/or vector(s); (vi) influence of temperature on virus survival and transmission; (vii) number of wildlife compartments/groups acting as reservoirs or amplifying hosts; (viii) increase of autochthonous wild mammals; and (ix) number of tick species vectors and their distribution. Our results support researchers in prioritizing studies targeting the most relevant drivers of emergence and increasing TBE incidence.

The current state of the problem of tick-borne encephalitis in Russia and the world

Relevance. Despite the successes achieved over the 85-year history of the study of tick-borne encephalitis (TBE), there are still many controversial and unresolved issues. It is obvious that in the second decade of the XXI century, this natural focal neuroinfection, as before, poses a great threat to public health not only in Russia, but also in endemic countries of the world.Aim. To present modern aspects of etiology, epidemiology, diagnosis, specific prevention of TBE in Russia and endemic countries of the world.Conclusions. Currently, there are 4 genotypes of the TBE virus: Far Eastern, European, Siberian and Baikal, each of which has its own area, pathogenic potential for humans. Nosoareal of TBE covers most of the territory of Russia, 29 European countries. Cases of TBE disease or viral activity are registered in six Asian countries. For the correct verification of the diagnosis, criteria for the diagnosis of cases of the disease have been developed, which mainly concern unvaccinated persons. Since highly effective etiotropic drugs for the treatment of TBE have not yet been developed, the only strategy for reducing the incidence of TBE is mass vaccination of the population of endemic regions. Due to the increase in the rate of vaccination in Russia and European countries, in order to improve epidemiological surveillance of TBE, standards for specific laboratory diagnosis of the disease among vaccinated persons, clarification of the causes of the incidence of vaccinated, as well as deaths among them, need to be clarified. In conditions of combination of natural foci of TBE and other tick-borne infections, it is important to develop diagnostic algorithms, including differential diagnosis of this disease with other infections transmitted by Ixodic ticks.

ОЦЕНКА ЭКОНОМИЧЕСКОГО УЩЕРБА ОТ КЛЕЩЕВОГО ВИРУСНОГО ЭНЦЕФАЛИТА В АРХАНГЕЛЬСКОЙ ОБЛАСТИ С ИСПОЛЬЗОВАНИЕМ ПОКАЗАТЕЛЯ «ПОТЕРЯННЫЕ ГОДЫ ПОТЕНЦИАЛЬНОЙ ЖИЗНИ»

Significance. The assessment of economic damage from infectious diseases is important for substantiating the ongoing preventive and anti-epidemic measures. It makes it possible to identify the most significant diseases and make effective management decisions to reduce the incidence. The average incidence of tick-borne encephalitis (TBE) in the Arkhangelsk region in 2004-2021 exceeds the Russian one 3.2 times. The Arkhangelsk region reports lethal cases every year. It is necessary to calculate the TBE economic damage to determine priority control measures and update preventive measures at the regional level. The purpose of the study is to calculate the economic damage from lethal cases of tick-borne encephalitis in the Arkhangelsk region and provide interpretations. Material and methods. The assessment of economic damage from lethal TBE cases was based on calculation of potential years of life lost (PYLL) according to Methodological recommendations [1]. The study used data on lethal TBE cases from the forms of Federal statistical observation # 2 "Information on infectious and parasitic diseases" in the Arkhangelsk region for 2011-2021, maps of epidemiological examination of TBE foci. Results. For the period from 2011 to 2021, the average economic damage incurred by the Arkhangelsk region because of the lost regional gross product associated with TBE deaths adjusted for inflation calculated on the basis of YPLL adds up to 12,136,771.6 Russian rubles per year. Conclusions. The economic damage calculation makes it possible to visualize the burden associated with TBE incidence in the Arkhangelsk region and substantiates the need to further improve preventive and anti-epidemic measures with regard to tick-borne encephalitis. Scope of application. The study results can be used to make management decisions to reduce the TBE incidence, including the development of plans and programs of preventive and anti-epidemic measures.

Meningitis and encephalitis in Poland in 2020.

Meningitis and/or encephalitis are one of the main infectious diseases of the nervous system. These diseases are most commonly caused by bacterial and viral etiological factors. In this publication, meningitis and/or encephalitis caused by Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae and those with a viral origin - in Poland, most often caused by tick-borne encephalitis virus - are presented in detail. In addition to epidemiological surveillance, immunoprophylaxis in the form of mandatory and recommended vaccinations is used in Poland to prevent these infections. The aim of this study was to to assess the epidemiological situation of meningitis and encephalitis in Poland, in 2020. To analyse the epidemiological situation of neuroinfections in Poland were used data sent to NIPH NIH - NRI by Voivodeship Sanitary and Epidemiological Stations and published in the annual bulletins: "Infectious diseases and poisonings in Poland in 2020" and "Protective vaccination in Poland in 2020" and individual epidemiological interviews registered in the EpiBaza system. In 2020, a total of 831 cases of meningitis and/or encephalitis were registered in Poland. This is a decrease in incidence of up to 62.9% compared to 2019. For infections of bacterial etiology, including cases of neuroborreliosis (incidence of 2.40 per 100,000), the number of cases decreased by 60.4% (from 931 to 369). In the viral infection group, there was a 64.9% decrease (from 1,318 to 462 cases). Of all registered cases, 56% were infections with a viral etiology. Compared to 2019, the number of cases with an S. pneumoniae etiology decreased by 61.3% and for N. meningitidis by 41.1%. It is interesting to note that, in the case of H. influenzae, we can speak of a 20% increase in cases compared to the previous year. In addition, we can see a decrease in the incidence of tick-borne encephalitis - from 265 in 2019 to 158 in 2020 (a decrease of 40.4%). Overall, a downward trend in incidence was shown for both bacterial andviral meningitis and/or encephalitis. The SARS-CoV-2 pandemic and the introduction of restrictions on personto-person contact and various forms of activity, resulting in a reduction in pathogen transmission, were key tothe significant reduction in the number of meningitis and/or encephalitis cases in 2020, but a reduction in theavailability of medical facilities or the completeness of case reports due to the burden of anti-epidemic measureson the Sanitary Inspectorate cannot be excluded either. Only in the case of cases caused by H. influenzae wasa slight increase observed compared to the previous year (12 versus 10 cases). Meningoencephalitis and/orencephalitis, due to its wide etiological range, poses a major challenge to the health care system, particularly interms of correct clinical diagnosis.

Can risk area designation help increase vaccination coverage for Tick-Borne Encephalitis? Evidence from German claims data

Background and objectivesAlthough vaccine preventable, the incidence of tick-borne encephalitis (TBE) increased in Germany from 2001 to 2021 by on average 2% each year, with a peak of more than 700 TBE infections documented in 2020. TBE-risk areas, as designated by district based on incidence of human cases, expanded north- and northeastward, present in 11 of the 16 Federal States as of 2022. Using claims data from a German statutory health insurance in the Federal States of Saxony and Thuringia (AOK PLUS), we aimed to assess whether official assignment of a district to a risk area had an impact on vaccination rates in Germany. MethodsThe data covered the period from 01/01/2010 to 31/12/2018 and included information on vaccine administrations from outpatient physicians. Yearly incident vaccination rates were reported overall and by district. To investigate the association between a new designation of an incident TBE-risk area and vaccination rates, a difference-in-difference analysis was conducted. ResultsOverall, the incident vaccination rates increased from 6.2 to 9.5 per 1,000 person-years between 2012 and 2018, with a peak of 12.2 in 2015. While districts that had been risk-areas for the whole study period had always a higher vaccination rate compared to districts that were never categorized as risk areas, the increase between 2012 and 2018 was comparable in the two groups (3.0 and 3.2 per 1,000 person-years, respectively). In contrast, districts that were newly designated risk districts during the study period experienced a significantly larger increase in vaccination rates, going from 5.8 to 14.7 per 1,000 person-years between 2012 and 2018, with a peak of 19.6 in 2015. ConclusionThe results suggest that the new designation of a district as risk area has a significant positive impact on vaccination rates, which is strongest immediately after designation of risk area.

Обоснование статистической модели для описания и прогноза рисков населения подвергнуться атакам иксодовых клещей

Incidence of tick-borne encephalitis and other tick-borne infections correlates with a number of people applying for medical aid due to tick bites. Obviously, the number of registered tick bites is proportionate to people’s economic and recreational activities on an endemic territory and the quantity of hungry ticks. In its turn, the quantity of ticks depends on abundance of main hosts for blood-feeding stages but with a certain time lag caused by their life cycle parameters such as molting to the next stage, diapauses, and apparent seasonality in a continental boreal climate zone. Our research goal was to analyze and synthesize an adequate formalized/parameterized statistical model to describe and predict risks of tick bites for population. To describe dynamics and to predict a number of people bitten by ticks exemplified by the Sverdlovsk region, we used several linear (by parameters) logistic regression models. We applied a multimodel inference framework to assess whether the observed dynamics was described adequately. Long-tern dynamics of the number of people bitten by ticks in the Sverdlovsk region is characterized with an occurring high-amplitude slow long-wave oscillation (circadecadal one, with a quasi-period being approximately 10 years) and a short-wave 2–3-year cyclicity. The former may be associated with climatic rhythm and socioeconomic trends; the latter may be caused by biotic factors. By using the logit-regression model, we showed that the number of small mammals, both in the previous year and at the beginning of the current tick activity season can be a valuable predictor of a risk for population to be bitten by ticks. Predictive values of the created statistical model adequately describe an initial time series of chances/probabilities of tick bites.

Substantiation of statistical model to describe and predict risks of tick bites for population

Incidence of tick-borne encephalitis and other tick-borne infections correlates with a number of people applying for medical aid due to tick bites. Obviously, the number of registered tick bites is proportionate to people’s economic and recreational activities on an endemic territory and the quantity of hungry ticks. In its turn, the quantity of ticks depends on abundance of main hosts for blood-feeding stages but with a certain time lag caused by their life cycle parameters such as molting to the next stage, diapauses, and apparent seasonality in a continental boreal climate zone. Our research goal was to analyze and synthesize an adequate formalized/parameterized statistical model to describe and predict risks of tick bites for population. To describe dynamics and to predict a number of people bitten by ticks exemplified by the Sverdlovsk region, we used several linear (by parameters) logistic regression models. We applied a multimodel inference framework to assess whether the observed dynamics was described adequately. Long-tern dynamics of the number of people bitten by ticks in the Sverdlovsk region is characterized with an occurring high-amplitude slow long-wave oscillation (circadecadal one, with a quasi-period being approximately 10 years) and a short-wave 2–3-year cyclicity. The former may be associated with climatic rhythm and socioeconomic trends; the latter may be caused by biotic factors. By using the logit-regression model, we showed that the number of small mammals, both in the previous year and at the beginning of the current tick activity season can be a valuable predictor of a risk for population to be bitten by ticks. Predictive values of the created statistical model adequately describe an initial time series of chances/probabilities of tick bites.

A Retrospective Analysis of Tick-borne Encephalitis in Children Treated in Kaunas Hospital During 2012 to 2019.

Lithuania has the highest tick-borne encephalitis (TBE) rates in Europe. Although TBE incidence in children is lower, it may still cause long-term consequences. So far pediatric epidemiological and clinical characteristics of TBE in Lithuania were not described. We performed a retrospective analysis of 87 cases of children who were hospitalized for TBE in Kaunas Hospital of the Lithuanian University of Health Sciences from 2012 to 2019. Each case was identified with neurological symptoms and positive serological tests. Around half of the children (50.6%) reported having a tick bite, whereas 6.9% stated having exposure to unpasteurized milk. Biphasic course of the disease occurred in 70.1% of the cases. The most common clinical symptoms were headache (100%), fever (100%), nausea (85.1%), vomiting (78.2%), drowsiness (67.8%) and general weakness (66.7%). Meningeal symptoms were present in 93.1% of the cases, and 93.1% of the children had at least one focal neurological sign (tremor 82.3%, impaired balance 73.6%). Isolated meningitis was diagnosed in 57.5%, meningoencephalitis in 41.4% and meningoencephalomyelitis in 1.1% of the cases. Majority of younger children (1-8 years old) had meningitis (77.3%), whereas 49.2% of older children (9-17 years old) had more severe forms of TBE. Cerebrospinal fluid pleocytosis was found in 94.3% of cases (average white blood cell count: 111.7 per μL, protein: 0.5 g/L). Higher levels of cerebrospinal fluid protein were associated with more severe forms of TBE and older age. Duration of the symptomatic disease lasted ≈11 days. Early residual signs were observed in 75.9% of all cases. The epidemiological and clinical characteristics of TBE in children in Lithuania are similar to those described in other countries. Only half of the subjects reported having a tick bite. Younger children tend to suffer from meningoencephalitis and meningoencephalomyelitis less frequently than elder ones. Focal neurological signs were commonly observed. Majority of children had lasting symptoms of TBE upon discharge from the hospital.

Incidence of Tick-Borne Encephalitis during the COVID-19 Pandemic in Selected European Countries.

Ixodes ricinus ticks are one of the most important vectors and reservoirs of infectious diseases in Europe, and tick-borne encephalitis (TBE) is one of the most dangerous human diseases transmitted by these vectors. The aim of the present study was to investigate the TBE incidence in some European countries during the COVID-19 pandemic. To this end, we analyzed the data published by the European Center for Disease Prevention and Control (ECDC) and Eurostat on the number of reported TBE and COVID-19 cases in 2020 and TBE cases in 2015–2019 (reference period). Significant differences in the TBE incidence were found between the analyzed countries. The highest TBE incidence was found in Lithuania (25.45/100,000 inhabitants). A high TBE incidence was also observed in Central European countries. In 12 of the 23 analyzed countries, there was significant increase in TBE incidence during the COVID-19 pandemic during 2020 compared to 2015–2019. There was no correlation between the incidence of COVID-19 and TBE and between the availability of medical personnel and TBE incidence in the studied countries. In conclusion, Central Europe and the Baltic countries are areas with a high risk of TBE infection. Despite the COVID-19 pandemic and imposed restrictions, the incidence of TBE is increasing in more than half of the analyzed countries.

Burden of Tick-Borne Encephalitis, Sweden.

In recent decades, the incidence of tick-borne encephalitis (TBE) in Sweden has increased. To calculate the burden of disease over a 17-year period, we analyzed data from the Swedish National Health Data Register for TBE cases diagnosed during 1998–2014. We compared healthcare use and sick leave associated with 2,429 persons with TBE with a referent cohort of 7,287 persons without TBE. Patients with TBE were hospitalized for significantly more days during the first year after disease onset (11.5 vs. 1.1 days), logged more specialist outpatient visits (3.6 vs. 1.2 visits), and logged more sick leave days (66 vs. 10.7 days). These differences generally increased over time. The case-fatality rate for TBE was 1.1%. Our calculated cost of TBE to society provides a baseline for decisions on immunization programs. Analyzing register data, our study adds to clinical studies of smaller cohorts and model-based studies that calculate disease burden.

Optimization of the system of planning measures for epidemiological control of the incidence of tick-borne encephalitis and Siberian tick typhus in regions with combined foci of these infections

Optimization of the system of planning measures for epidemiological control of the incidence of tick-borne encephalitis and Siberian tick typhus in regions with combined foci of these infections

Aanalyzing risks of incidence of tick-borne encephalitis in areas with different climatic and geographical conditions

Ticks are natural reservoirs and vectors of a virus that is an infectious agent of tick-borne encephalitis, a communicable disease with great medical and social significance. Tick-borne encephalitis (TBE) is widely spread in Arkhangelsk region (AR) located in the Arctic zone in Russia where substantial climatic changes are taking place at the moment. Our research involved examining spatial and temporal distribution of numbers of people bitten by ticks, a number of people bitten by ticks per 100 thousand, a number of TBE cases and TBE incidence in districts and settlements in AR. We calculated relative risks of TBE incidence among people bitten by ticks in AR from 1980 to 2019. We analyzed dynamics of indicators showing numbers of people bitten by ticks per 100 thousand and TBE incidence among people living in Arkhangelsk region. The analysis revealed that a number of bitten people grew slowly in 1980–1990, then there was an exponential growth in 1990–2010, and then the trend stabilized in 2010–2019. Dynamics of TBE incidence was completely in line with changes in number of bitten people up to 2014 but there was a substantial drop in TBE incidence after that. Spatial distribution of numbers of bitten people and TBE incidence revealed that average number of bitten people amounted to 25.1 per 100 thousand in the northern districts in 1980–2019 and was statistically significantly lower than in the central and southern districts (р &lt; 0.001). Average long-term incidence was the highest (7.9 per 100 thousand) in the southern districts in comparison with the central (3.0 per 100 thousand; р&lt;0.001) and northern ones (0.7 per 100 thousand; р&lt;0.001). Maximum relative risks of TBE incidence was detected in the southern districts in 1990–1999 (38.8) in comparison with the northern ones. We made an assumption about probable reasons for declining TBE incidence in Arkhangelsk region detected over the last years given the growing numbers of bitten people.

Анализ риска заболеваемости клещевым вирусным энцефалитом в районах с разными климатогеографическими условиями

Ticks are natural reservoirs and vectors of a virus that is an infectious agent of tick-borne encephalitis, a communicable disease with great medical and social significance. Tick-borne encephalitis (TBE) is widely spread in Arkhangelsk region (AR) located in the Arctic zone in Russia where substantial climatic changes are taking place at the moment. Our research involved examining spatial and temporal distribution of numbers of people bitten by ticks, a number of people bitten by ticks per 100 thousand, a number of TBE cases and TBE incidence in districts and settlements in AR. We calculated relative risks of TBE incidence among people bitten by ticks in AR from 1980 to 2019. We analyzed dynamics of indicators showing numbers of people bitten by ticks per 100 thousand and TBE incidence among people living in Arkhangelsk region. The analysis revealed that a number of bitten people grew slowly in 1980–1990, then there was an exponential growth in 1990–2010, and then the trend stabilized in 2010–2019. Dynamics of TBE incidence was completely in line with changes in number of bitten people up to 2014 but there was a substantial drop in TBE incidence after that. Spatial distribution of numbers of bitten people and TBE incidence revealed that average number of bitten people amounted to 25.1 per 100 thousand in the northern districts in 1980–2019 and was statistically significantly lower than in the central and southern districts (р &lt; 0.001). Average long-term incidence was the highest (7.9 per 100 thousand) in the southern districts in comparison with the central (3.0 per 100 thousand; р&lt;0.001) and northern ones (0.7 per 100 thousand; р&lt;0.001). Maximum relative risks of TBE incidence was detected in the southern districts in 1990–1999 (38.8) in comparison with the northern ones. We made an assumption about probable reasons for declining TBE incidence in Arkhangelsk region detected over the last years given the growing numbers of bitten people.

Detection of tick-borne pathogens in wild birds and their ticks in Western Siberia and high level of their mismatch.

The Tomsk region located in the south of Western Siberia is one of the most high-risk areas for tick-borne diseases due to elevated incidence of tick-borne encephalitis and Lyme disease in humans. Wild birds may be considered as one of the reservoirs for tick-borne pathogens and hosts for infected ticks. A high mobility of wild birds leads to unpredictable possibilities for the dissemination of tick-borne pathogens into new geographical regions. The primary goal of this study was to evaluate the prevalence of tick-borne pathogens in wild birds and ticks that feed on them as well as to determine the role of different species of birds in maintaining the tick-borne infectious foci. We analysed the samples of 443 wild birds (60 species) and 378 ticks belonging to the genus Ixodes Latraille, 1795 collected from the wild birds, for detecting occurrence of eight tick-borne pathogens, the namely tick-borne encephalitis virus (TBEV), West Nile virus (WNV), and species of Borrelia, Rickettsia, Ehrlichia, Anaplasma, Bartonella and Babesia Starcovici, 1893, using RT-PCR/or PCR and enzyme immunoassay. One or more tick-borne infection markers were detected in 43 species of birds. All markers were detected in samples collected from fieldfare Turdus pilaris Linnaeus, Blyth's reed warbler Acrocephalus dumetorum Blyth, common redstart Phoenicurus phoenicurus (Linnaeus), and common chaffinch Fringilla coelebs Linnaeus. Although all pathogens have been identified in birds and ticks, we found that in the majority of cases (75.5 %), there were mismatches of pathogens in birds and ticks collected from them. Wild birds and their ticks may play an extremely important role in the dissemination of tick-borne pathogens into different geographical regions.

Incidence and occurrence of tick-borne encephalitis and neuroborreliosis in Germany

Given the nationwide distribution of the vector, Ixodes ricinus, both neuroborreliosis and tick-borne encephalitis (TBE) might be expected to occur throughout Germany. However, cases of neuroborreliosis and TBE have so far only been reported in certain German states and counties. The aim of this survey therefore was to investigate the possible occurrence of TBE in regions not designated as known risk areas and the spread and incidence of neuroborreliosis throughout Germany. Data were collected by means of a questionnaire which was sent to 305 neurological clinics in Germany. Only twenty-two of them (7.2%) participated in a prospective, and 52 (17%) in a retrospective survey, therefore the significance of the study is limited. Cases of TBE were detected in five counties (Barnim, Dessau-Roßlau, Western Pomerania-Ruegen, Saarbruecken, Uckermark) that were not known so far as areas of risk according to the definition of the German Robert-Koch-Institute (RKI). The median incidence of TBE in various counties was 1.24 cases with a range from 0.19 to 20 cases per 100,000 inhabitants/year. Illnesses from neuroborreliosis were reported from all 61 counties, where clinics participated in the study. The incidence here varied between 0.19 and 23.4 cases with a median of 3.0 cases per 100,000 inhabitants/year. In areas where both diseases occurred, their incidence differed greatly from each other. The survey shows the occurrence of TBE in several counties in eastern Germany that are not defined as risk areas by the RKI and an incidence of neuroborreliosis in Germany that is significantly higher than reported to the public health authorities.

Incidence of tick-borne encephalitis in the Republic of Bashkortostan (Russia) in XXI century

Tick-borne encephalitis (TBE) is transmissive zoonotic disease often severely affecting nervous system. A number of studies conducted in different geographical areas demonstrated evolution of TBE. Official registration of the cases of TBE in the Republic of Bashkortostan started approximately 70 years ago. Aim. To assess the main clinical and epidemiological features of TBE in XXI century and compare them with the data registered in XX century.

Effect of environmental variables on incidence of tick-borne encephalitis, leptospirosis and tularaemia.

Potential effect of three environmental variables (population density of rodents, global weather in the form of the North Atlantic Oscillation (NAO) index, and acorn crop) on human morbidity rate of three zoonoses: tick-borne encephalitis (TBE), leptospirosis and tularaemia were analysed in the Czech Republic for the period 1970-1990. The Pearson's correlation analysis was used. The correlation analysis revealed that the significant factor for explaining annual morbidity rates of these zoonoses was the abundance of common voles (Microtus arvalis) in the current year (for leptospirosis) or in the previous calendar year (for TBE and tularaemia). The two other environmental variables tested (NAO index and acorn production) do not seem to play a significant role in these zoonoses in Central Europe.