Incidence Of Tick-borne Encephalitis Research Articles

Ecological and epidemiological characteristics of tick-borne encephalitis and ixodic tick-borne borreliosis incidence according to the data of the Arkhangelsk region for 2012–2022

BACKGROUND: The increase of ticks infected with borrelia and tick-borne encephalitis virus, as well as the impact of anthropogenic factor on the ecosystem of the northern region determines the need to study possible risk factors and epidemiological trends in the incidence of tick-borne encephalitis and ixoid tick-borreliosis. AIM: To conduct a retrospective ecological and epidemiological analysis of regional peculiarities of the epidemic process of tick-borne encephalitis and ixoid tick-borreliosis in the Arkhangelsk region in comparison with similar indicators in the North-West Federal District and Russia for 2012–2022. MATERIALS AND METHODS: The work was carried out in accordance with the ecological research design. Statistical data of the Unified Interdepartmental Information and Statistical System, as well as statistical annual forms of the Department of the Federal Service for Supervision of Consumer Rights Protection and Human Welfare in Russia and the Arkhangelsk region were used as the information base. The registered cases of tick-borne encephalitis and ixoid tick-borreliosis morbidity in the Arkhangelsk region, as well as in Russia and the Northwestern Federal District as a whole for 2012–2022 were evaluated. Time series analysis was performed using Microsoft Excel 2019. The study also analyzes the dynamics of climatic factors in the Arkhangelsk region and its possible impact on the distribution and migration of ixodid ticks across the territory of the European North of Russia. Correlations were assessed by evaluating Pearson’s correlation criterion using the Google Collaboratory interface. RESULTS: The number of tick bites in the Arkhangelsk region throughout the entire study period significantly exceeds the similar indicator (per 100 thousand population) in Russia. The incidence of tick-borne encephalitis in the Arkhangelsk region significantly exceeds that in both the Russian Federation and the Northwestern Federal District, and exceeded the average annual rate in Russia more than 3 times, although it had a faster rate of decline (5.7% vs. 3.7% annually). The incidence of ixoid tick-borreliosis has a paradoxical character due to the fact that throughout almost the whole period it is below the all-Russian level (3.19 per 100,000 population in Arkhangelsk region against 4.41 in the Russian Federation), while the incidence in the Northwestern Federal District is 1.3 times higher on average. CONCLUSIONS: During the last decade the incidence of tick-borne encephalitis in the Arkhangelsk region remains stably high in comparison with both the Russian Federation and the Northwestern Federal District. The incidence of ixoid tick-borreliosis corresponds to the long-term average for Russia, with a more pronounced downward trend (4.7% vs. 1.7%). The territory of the Arkhangelsk region is subject to the trend of increasing average annual temperatures, and anthropogenic interventions, in particular, abundant deforestation, lead to the destruction of established ecosystems and open new opportunities and territories for ticks, which in the future may negatively affect the established trends of morbidity. The analysis confirms the need to develop and adopt organizational measures aimed at the development of epidemiological and epizootological monitoring.

Tick-Borne Encephalitis the situation in Poland 2024 - concern that warrants attention?

Introduction Tick-borne encephalitis (TBE) is a zoonotic infectious disease and the leading cause of viral meningitis in Poland. In recent years, there has been a marked increase in TBE cases, a trend possibly linked to global climate changes that are facilitating the spread of its primary vector, the Ixodes Ricinus tick species. Aim of the Study This paper aims to review the current understanding of tick-borne encephalitis and emphasize the importance of preventive measures. Materials and Methods This review compiles data from various sources, including recent epidemiological studies, clinical reports, and public health records. It examines the clinical progression of TBE, from the initial viremic phase to the possible development of severe neurological symptoms. Epidemiological data are analyzed to identify trends in TBE incidence, with a particular focus on how climate change affects the distribution and activity of tick populations. Conclusions The review underscores that TBE is an escalating public health issue in Poland, with incidence rates increasing alongside climate-induced changes in tick habitats. Effective prevention, particularly through vaccination, is essential for reducing the impact of TBE. However, despite the availability of effective vaccines, vaccination rates remain low in Poland. This highlights the need for improved public health efforts to promote vaccination and educate at-risk populations. Addressing the TBE threat requires a comprehensive strategy that includes better surveillance, preventive measures, and strong public health initiatives to protect against this increasingly common disease.

Tick-borne Encephalitis Clinical Characteristics in Adult Patients: A 10-year Retrospective Study in Stockholm, Sweden.

The incidence of Tick-borne encephalitis (TBE) has increased during the last decades in Europe. Our aim was to assess the clinical characteristics and outcome of TBE patients in Region Stockholm, as a high-risk area in Sweden. The notification database at the regional Department of Communicable Disease Control and Prevention was used to identify TBE cases during 2006-2015. Clinical data was retrieved from the included patients' medical records. The associations of specific variables to predefined outcomes of disease severity were evaluated with multivariate logistic regression models. Of 1004 identified TBE cases, 703 adult patients were included. Sixty-one percent were men, and the median age was 50 years (range 18-94). The majority were non-vaccinated. Comorbidity was present in 34%, and 4% had immunomodulatory therapy. Seventy-five percent were hospitalised, and 11% had severe disease. More than 70% of the 79 patients followed up for more than 6 months had persisting symptoms. The case fatality rate was 1.4%, with 15% in the group with immunomodulatory treatment. In the multivariate analysis, severe disease was associated with underlying comorbidities, age ≥50 years, and previous complete TBE vaccination. This is the largest cohort of TBE patients in Scandinavia. Our findings of a more severe course of disease in patients of older age, with immunomodulatory therapy, with comorbidities, and vaccination breakthrough infections must be interpreted in the context of hospitalised patients. Optimised prevention is needed for patients with immunomodulatory therapy, given the considerable case fatality rate. Follow-up visits and rehabilitation should be better standardised.

Global Seroprevalence of Tick-Borne Encephalitis Antibodies in Humans, 1956-2022: A Literature Review and Meta-Analysis.

Despite the availability of tick-borne encephalitis (TBE) vaccines, the incidence of TBE is increasing. To understand the historical patterns of infection, we conducted a global meta-analysis of studies before December 2023 reporting human antibody prevalence against TBEV (TBE virus) among general or high-risk population groups stratified by country, collection year, serological method, and vaccination status. Pooled data were compared within groups over time by random-effects modeling. In total, 2403 articles were retrieved; 130 articles published since 1959 were included. Data were extracted from 96 general populations (117,620 participants) and 71 high-risk populations (53,986 participants) across 33 countries. Germany had the most population groups (21), and Poland had the most participants (44,688). Seven serological methods were used; conventional IgG/IgM ELISAs were the most common (44%). Four studies (1.7%) used NS1-ELISA serology. Between 1956-1991 and 1992-2022, anti-TBEV seroprevalence remained at ~2.75% across all population groups from "high-risk" areas (p = 0.458) but decreased within general populations (1.7% to 1%; p = 0.001) and high-risk populations (5.1% to 1.3%; p < 0.001), possibly due to differences in the study methodologies between periods. This global summary explores how serological methods can be used to assess TBE vaccination coverage and potential exposure to TBEV or measure TBE burden and highlights the need for standardized methodology when conducting TBE seroprevalence studies to compare across populations.

Incidence, healthcare resource utilization and costs of hospitalized patients with tick-borne encephalitis (TBE) in Italy

ObjectiveOur study's objective was to assess the incidence trends and healthcare resource utilization of hospitalizations for Tick-Borne Encephalitis (TBE) and associated costs in Italy in order to improve public awareness and preventive measures. MethodsThis retrospective observational study was based on the Italian Ministry of Health's Hospital Discharge Record (HDR) database. Data were gathered across Italy from 2015 to 2019, selecting hospitalizations with ICD-9 code 063 related to TBE, both in primary and secondary diagnoses. For each year, we collected the following variables: number of hospitalizations, hospitalization rate, mortality rate, mean length of hospital stay, hospital ward, and cost of hospitalization. ResultsThere were a total of 237 hospitalizations from 2015 to 2019; 62 % of those were male. The lowest number of TBE hospitalizations was in 2015 (21 cases, corresponding to 0.35 per million inhabitants), the highest in 2019 (64 cases, 1.04 per million inhabitants). The summer months saw a greater than average number of hospitalizations. For the years analyzed, the cumulative number of cases peaked in June (54 cases), July (46 cases), and August (35 cases). There were only two deaths registered in our study sample. TBE cases were mostly localized in the North-Eastern regions of Italy. TBE incidence during the study period in the most affected areas were: Autonomous Province of Trento, ranging from 11.2 to 42.3 per million inhabitants, Autonomous Province of South Tyrol, from 0 to 21.1 per million inhabitants, and Veneto Region, from 2.6 to 4.5 per million inhabitants. In the study period, the average length of hospital stay was largely stable ranging from 10.6 days to 12.8 days, with related costs ranging from 5,813.7 € to 7,352.5 €. ConclusionsAccording to our data, the majority of TBE hospitalizations occur in North-East Italy with an increasing trend over the analyzed period. Even though Italy has fewer TBE cases than other neighboring European countries, the health and economic impact can be high in the affected areas.

Epidemiological Situation on Tick-Borne Encephalitis in the Russian Federation in 2014–2023 and Short-Term Forecast of the Incidence for 2024

The aim of the review was to conduct a comparative analysis of the epidemiological situation on tick-borne encephalitis (TBE) over 2014–2023 in the constituent entities of the Russian Federation located in the European and Asian parts of the country and to give a forecast of incidence for 2024. The incidence of TBE in 2023 only marginally decreased as compared to the peak values in 2022, which leveled down the ten-year trend towards reduction. Grouping of the entities of the Russian Federation according to the average incidence of TBE over a decade made it possible to classify 17 of them as regions of low, 15 – of medium, and 17 – of high epidemiological risk. In general, the epidemiological situation regarding TBE is more unfavorable in the Asian part of the country. A list of species of Ixodidae ticks, the main vectors of the tick-borne encephalitis virus, is provided, as well as subtypes and genetic variants of the latter, identified in the European and Asian parts of the country. The peculiarities of the epidemiological situation on TBE and the scope of preventive measures undertaken in Russia in 2023 are considered. It is shown that there are no clearly outlined trends in the nature of changes in the incidence of TBE in endemic federal districts and entities of the country, and the expected incidence rates in 2024 will remain at the long-term average level.

Phylogenetic characterisation of tick-borne encephalitis virus from Lithuania.

The Baltic states are the region in Europe where tick-borne encephalitis (TBE) is most endemic. The highest notification rate of TBE cases is reported in Lithuania, where the incidence of TBE has significantly increased since 1992. A recent study reported 0.4% prevalence of TBE virus (TBEV) in the two most common tick species distributed in Lithuania, Ixodes ricinus and Dermacentor reticulatus, with the existence of endemic foci confirmed in seven out of Lithuania's ten counties. However, until now, no comprehensive data on molecular characterisation and phylogenetic analysis have been available for the circulating TBEV strains. The aim of this study was to analyse TBEV strains derived from I. ricinus and D. reticulatus ticks collected from Lithuania and provide a genotypic characterisation of viruses based on sequence analysis of partial E protein and NS3 genes. The 54 nucleotide sequences obtained were compared with 81 TBEV strains selected from the NCBI database. Phylogenetic analysis of the partial E and NS3 gene sequences derived from 34 Lithuanian TBEV isolates revealed that these were specific to Lithuania, and all belonged to the European subtype, with a maximum identity to the Neudoerfl reference strain (GenBank accession no. U27495) of 98.7% and 97.4%, respectively. The TBEV strains showed significant regional genetic diversity. The detected TBEV genotypes were not specific to the tick species. However, genetic differences were observed between strains from different locations, while strains from the same location showed a high similarity.

Assessment of registered and hidden epidemic process of tick-borne encephalitis in the Republic of Karelia

Introduction. The incidence of tick-borne encephalitis in the Russia remains relevant. The assessment of the epidemic process in the Republic of Karelia is important not only in terms of understanding its general patterns, but in connection with the growth of tourist attendance in the region.&#x0D; Aims: To assess the current epidemic situation of tick-borne encephalitis in the Republic of Karelia, and to compare the characteristics of registered and hidden epidemic processes.&#x0D; Materials and methods. The risk of infection and incidence were estimated based on the analysis of the registered cases of seeking medical help in connection with tick bites, the results of a study of tick-borne encephalitis virus (TBEV) infection rate in ticks, and the epidemiological investigation of cases of tick-borne encephalitis in 1992–2022. Clinical, gender and age structure, territorial distribution of patients and victims of the tick bites were compared with the results of serological studies of 2379 blood samples of the adult population, conducted in 2011–2022.&#x0D; Results. Infection rates of ticks removed from humans ranged from 23.6–27.0% in 2002–2005 to 1.0% in 2022. In 2004, the TBEV antigen was detected in mosquitoes. The territory of risk is the southern part of Republic. However, the increase in number of cases of seeking medical help was observed in the northern part of Republic. The incidence rates exceeded the national average, especially in 2003–2004 (15.3–11.6 per 100 thousand). In 2021–2022, it decreased to 1.8–1.5 per 100,000. The dynamics of incidence had a high-degree correlation with the dynamics of seeking medical help and infection rates in ticks (R = 0.92 and 0.73). The reported incidence was lower than the estimated risk of infection. The meningeal forms of infection were most often diagnosed. The risk of the disease was higher in the elderly and in men, which was determined by the conditions of infection. Antibodies to TBEV were detected in 11.8 ± 0.7% of the examined persons.&#x0D; Conclusion. A steady decrease in rates of registered tick-borne encephalitis incidence has been revealed in the Republic of Karelia, mainly due to the action of biological and natural factors. The assessment of seroprevalence made it possible to reveal the hidden part of the epidemic process.

Epidemic status in Russia’s Northwestern Federal District: tick-borne encephalitis and ixodes tick-borne borreliosis (lyme disease), 2002–2021

The study's objective was to reveal trends in tick-borne encephalitis (TBE) and Ixodes tick-borne borreliosis (ITBB) epidemic processes in Russia's Northwestern Federal District (NWFD) in 2002–2021. In the NWFD during the analyzed period, more than 1.1 million patients sought medical help following tick bites (14% of all cases registered nationwide). The long-term average tick bite incidence rate in the NWFD exceeded the nation-wide value: 409.5 and 280.7, respectively. In the NWFD, the highest long-term average tick bite incidence rates were recorded in Vologda Oblast, Pskov Oblast, and Novgorod Oblast. The tick bite incidence rate tended to grow in the NWFD, as well as nationally. The growth in tick bite incidence was statistically significant in the Republic of Komi, Kaliningrad Oblast, and Arkhangelsk Oblast. In 2002–2021, more than 6000 TBE cases were registered in the NWFD (11% of all cases registered nationwide), and the TBE long-term average incidence rate in the NWFD exceeded the national value: 2.3 and 2.0, respectively. The Republic of Karelia, Arkhangelsk Oblast, and Vologda Oblast were three NWFD subjects with high TBE epidemical hazard. TBE incidence in the analyzed period tended to decrease, both in the NWFD and nationwide. A statistically significant decrease in TBE incidence was revealed in St. Petersburg, in the Republic of Karelia, in Novgorod Oblast, and in Leningrad Oblast. About 22 000 ITBB cases were reported in the NWFD during the analyzed period (15% of all ITBB cases in Russia). The ITBB long-term average incidence rate in the NWFD exceeded the national value: 7.9 and 4.9, respectively. Vologda Oblast, Kaliningrad Oblast, and Pskov Oblast were three NWFD subjects with high epidemical hazard in terms of ITBB. ITBB incidence during the analyzed period tended to decrease, both in the NWFD and nationwide. The decrease in ITBB incidence was statistically significant in Vologda, Kaliningrad, Novgorod, Leningrad and Pskov Oblasts, as well as in St. Petersburg. In the Republic of Komi, in contrast to other NWFD subjects or national data, there was an uptrend in both TBE and ITBB incidence.

Outdoor recreation, tick borne encephalitis incidence and seasonality in Finland, Norway and Sweden during the COVID-19 pandemic (2020/2021)

ABSTRACTDuring the pandemic outdoor activities were encouraged to mitigate transmission risk while providing safe spaces for social interactions. Human behaviour, which may favour or disfavour, contact rates between questing ticks and humans, is a key factor impacting tick-borne encephalitis (TBE) incidence.We analyzed annual and weekly TBE cases in Finland, Norway and Sweden from 2010 to 2021 to assess trend, seasonality, and discuss changes in human tick exposure imposed by COVID-19. We compared the pre-pandemic incidence (2010–2019) with the pandemic incidence (2020–2021) by fitting a generalized linear model (GLM) to incidence data.Pre-pandemic incidence was 1.0, 0.29 and 2.8 for Finland, Norway and Sweden, respectively, compared to incidence of 2.2, 1.0 and 3.9 during the pandemic years. However, there was an increasing trend for all countries across the whole study period. Therefore, we predicted the number of cases in 2020/2021 based on a model fitted to the annual cases in 2010–2019. The incidences during the pandemic were 1.3 times higher for Finland, 1.7 times higher for Norway and no difference for Sweden. When social restrictions were enforced to curb the spread of SARS-CoV-2 there were profound changes in outdoor recreational behavior. Future consideration of public health interventions that promote outdoor activities may increase exposure to vector-borne diseases.

Tick-Borne Encephalitis (TBE): From Tick to Pathology.

Tick-borne encephalitis (TBE) is a viral arthropod infection, endemic to large parts of Europe and Asia, and is characterised by neurological involvement, which can range from mild to severe, and in 33-60% of cases, it leads to a post-encephalitis syndrome and long-term morbidity. While TBE virus, now identified as Orthoflavivirus encephalitidis, was originally isolated in 1937, the pathogenesis of TBE is not fully appreciated with the mode of transmission (blood, tick, alimentary), viral strain, host immune response, and age, likely helping to shape the disease phenotype that we explore in this review. Importantly, the incidence of TBE is increasing, and due to global warming, its epidemiology is evolving, with new foci of transmission reported across Europe and in the UK. As such, a better understanding of the symptomatology, diagnostics, treatment, and prevention of TBE is required to inform healthcare professionals going forward, which this review addresses in detail. To this end, the need for robust national surveillance data and randomised control trial data regarding the use of various antivirals (e.g., Galidesivir and 7-deaza-2'-CMA), monoclonal antibodies, and glucocorticoids is required to improve the management and outcomes of TBE.

Tick-Borne Encephalitis-Review of the Current Status.

The tick-borne encephalitis virus (TBEV) is the arboviral etiological agent of tick-borne encephalitis (TBE), considered to be one of the most important tick-borne viral diseases in Europe and Asia. In recent years, an increase in the incidence of TBE as well as an increasing geographical range of the disease have been noted. Despite the COVID-19 pandemic and the imposition of restrictions that it necessitated, the incidence of TBE is rising in more than half of the European countries analyzed in recent studies. The virus is transmitted between ticks, animals, and humans. It seems that ticks and small mammals play a role in maintaining TBEV in nature. The disease can also affect dogs, horses, cattle, and small ruminants. Humans are incidental hosts, infected through the bite of an infected tick or by the alimentary route, through the consumption of unpasteurized milk or milk products from TBEV-infected animals. TBEV infections in humans may be asymptomatic, but the symptoms can range from mild flu-like to severe neurological. In Europe, cases of TBE are reported every year. While there is currently no effective treatment for TBE, immunization and protection against tick bites are critical in preventing this disease.

Dynamics of the Epidemic Process of Tick-Borne Encephalitis in Irkutsk Region in 2001–2021

The aim of this work was to analyze the spatial and temporal features of the epidemic process dynamics of tick-borne encephalitis (TBE) in Irkutsk Region in 2001–2021.Materials and methods. The data of the Rospotrebnadzor Administration for the Irkutsk Region, the Reference Center of the Irkutsk Research Anti-Plague Institute, the materials of the state statistical reporting form No. 2 “Information on infectious and parasitic diseases”, and scientific publications were analyzed. The chronological and chorological features of the change in the incidence of TVE have been traced. In the latter case, the administrative-territorial formations (ATF) of the subject were differentiated by epidemiological risk groups over two ten-year periods: 2001–2010 and 2011–2020. At each time interval, the grouping of areas according to the level of TBE incidence was carried out using the calculation of 95% confidence interval. Time sequences of observations were analyzed using the construction of regression equations. Standard methods of variation statistics in the Microsoft Excel were deployed.Results and discussion. Over the course of the 21st century, the incidence of TBE in Irkutsk Region has been declining. Based on 2001–2010 data, there were no cases of TBE in six ATF, and endemic areas were divided into three groups: with low (15 districts), medium (6) and high (8) incidence of TBE. A separate assessment of morbidity rates was conducted in the administrative center of the entity, the city of Irkutsk. In 2011–2020, the structure of ATF with varying epidemiological risk of TBE underwent a change. Six non-endemic areas, groups of low (12 ATFs), medium (9), high (6) and very high (2) epidemiological risk were identified. The spatial arrangement of high epidemiological risk zones changed, and their area increased. Each ATF cluster with different TBE incidence in 2011–2020 is characterized by the number of TBE cases and the volume of measures to prevent the infection. It is concluded that preventive measures were insufficient in ATF groups of high and very high epidemiological risk.

Analysis of the Dynamics of Tick-Borne Encephalitis Incidence and the Number of People who Appealed to Medical Organizations about Tick Bites in the European North of Russia

In recent decades, a significant increase in the incidence of tick-borne viral encephalitis (TBVE) and the number of people attacked by ticks has been recorded in the European North of Russia.The aim of the study was to analyze the dynamics of the TBVE incidence and the number of people who appealed to medical organizations regarding tick bites in the European North of Russia.Materials and methods. We used the Form No. 2 “Information on infectious and parasitic diseases”, the results of operational seasonal monitoring of TBVE, presented by the Rospotrebnadzor Administrations of the respective territories for our study. Statistical data processing was performed using the Microsoft Excel program. Display of the results on the map was carried out in the geographic information system ESRI ArcMap.Results and discussion. Combined analysis of the data on the number of cases and TBVE incidence, the number of people who appealed to medical organizations about tick bites and the number of people seeking advice about tick bites per 100 thousand population for the Arkhangelsk Region, the Republics of Karelia and Komi and their municipal districts has been performed. The mean values and gradients of the number of cases, incidence (2010–2020), the number of people who appealed to medical organizations regarding tick bites, and the number of people seeking treatment for tick bites per 100 000 population (2002–2020) have been calculated; maps of average values and gradients constructed. The incidence and the number of cases remain at the high level, exceeding the national average, but have been declining in the last decade. The number of people who appealed to medical organizations and the appealability of the population about tick bites per 100 000 of the population remain at a consistently high level and show no downward trend. The incidence and appealability of the population due to tick bites per 100 thousand of the population is spreading in a northerly direction, covering new territories in the Arctic zone. The main driving force behind the observed epidemic situation in the European North of Russia is the natural processes of climate change.

Tick-borne encephalitis in children.

The incidence of tick-borne encephalitis in Norway is increasing. The risk of infection shows considerable geographical variations, with clusters of cases in certain municipalities in the counties of Agder, and Vestfold and Telemark. There is also a major variation in clinical presentation. Only a small number of cases of tick-borne encephalitis in children have been reported in Norway, and the condition may be underdiagnosed. We present a clinical review, including two case studies, that focuses on the clinical presentation and diagnosis of tick-borne encephalitis in children.

Similarities and differences in the characteristics of the epidemical process tick-borne encephalitis and Lyme borreliosis

Objective: To identify common and distinctive characteristics of the epidemical process of tick-borne encephalitis and Lyme borreliosis on the example of the Republic of Karelia.Materials and methods. The frequency of infected tick bites, dynamics, intensity, territorial, gender, age and social features of the incidence of tick-borne encephalitis and Lyme borreliosis in 2000–2021 were analyzed according to official statistics, epidemiological examination of foci and laboratory studies. The results of studies of 2379 blood samples of adults who were not ill and not vaccinated against tick-borne encephalitis for the presence of antibodies to the virus were analyzed.Results. The virulence of ticks in 2000–2021 decreased from 23.6 to 1.3%, infection with borrelia at the level of 13.4– 38.4%. The average long-term incidence rates of tick-borne encephalitis and Lyme borreliosis were 6.2 and 6.6 per 100 thousand, the dynamics of incidence had an average pronounced downward trend, correlated with the dynamics of requests for medical care of the population affected by ticks. The main clinical form of tick–borne encephalitis is meningeal (48%). Non-erythemic forms of borreliosis in recent years amounted to 39.1%. Antibodies of class G to tick-borne encephalitis virus were detected in 11.8±0.7% of the examined individuals. The territory of risk of infection with tick-borne encephalitis and Lyme borreliosis is the central and eastern part of the south of the Republic, where I.persulcatus dominates. The proportion of urban residents among patients with both infections is higher, but the incidence of urban and rural populations did not have significant differences. The incidence rates of tick-borne borreliosis in persons aged 40-49, 50-59 and 60 years and older are 1.6-2.2 times higher than those of tick-borne encephalitis, but the difference is not significant. At working age, the percent of men is higher than women, there are no differences among the elderly.Conclusions: Similar and different features of the epidemic process of tick-borne encephalitis and tick-borne borreliosis have been identified, which should be taken to improving the detection of diseases, predicting the situation and planning preventive measures.

Development of ahighly purified tick-borne encephalitis vaccine : Apersonal historical account.

Before the advent of avaccine, infections with tick-borne encephalitis (TBE) virus in Austria led to the hospitalization of several hundred and, due to underreporting, possibly more than thousand patients with severe neurological disease every year. In the late 1960s and early 1970s, this country had the highest recorded morbidity of TBE in Europe, but similar endemic risk areas exist in many other European countries as well as Central and Eastern Asia. In this article, Idescribe my personal recollections of the development of ahighly purified TBE vaccine in the late 1970s, to which Icontributed as ayoung post-doctoral scientist mentored by Christian Kunz (then director of the Institute of Virology at the Medical Faculty, University of Vienna) in acollaboration with the Austrian biopharmaceutical company Immuno. Low reactogenicity of the newly developed vaccine was aprerequisite for mass vaccination campaigns in Austria that started in the early 1980s. Because of its excellent immunogenicity, broad application of the highly purified vaccine paved the way for adramatic reduction of the incidence of TBE in Austria, which is outstanding in Europe and referred to as an Austrian success story of immunoprophylaxis.

Effectiveness of Tick-borne Encephalitis Vaccines in Children, Latvia, 2018-2020.

Tick-borne encephalitis (TBE) is an infection by the tick-borne encephalitis virus (TBEV) with symptoms of central nervous system inflammation. TBE is endemic in Latvia and other parts of Europe. TBE vaccination is recommended for children in Latvia. TBE vaccine effectiveness (VE) was estimated in Latvia, a country with high TBE incidence, providing the first VE estimates against a range of TBEV infection outcomes in children 1-15 years-of-age. Rīga Stradinš University conducted nationwide surveillance for suspected TBE cases. Serum and cerebrospinal fluid were ELISA tested for TBEV-specific IgG and IgM antibodies. A fully vaccinated child was an individual who had received the 3-dose primary series and appropriately timed boosters. The proportion of laboratory-confirmed TBE cases fully vaccinated (PCV) was determined from interviews and medical records. The proportion of the general population fully vaccinated (PPV) was determined from national surveys conducted in 2019 and 2020. TBE VE in children 1-15 years-of-age was estimated using the screening method: VE = 1 - [PCV/(1 - PCV)/PPV/(1 - PPV)]. From 2018 to 2020, surveillance identified 36 TBE cases in children 1-15 years-of-age; all were hospitalized, 5 (13.9%) for >12 days. Of the TBE cases, 94.4% (34/36) were unvaccinated compared with 43.8% of children in the general population. VE against TBE hospitalization in children 1-15 years-of-age was 94.9% (95% confidence interval 63.1-99.3). In 2018-2020, vaccination in children 1-15 years-of-age averted 39 hospitalized TBE cases. Pediatric TBE vaccines were highly effective in preventing TBE in children. Increasing TBE vaccine uptake in children is essential to maximize the public health impact of TBE vaccination.

Correlation between airborne pollen data and the risk of tick-borne encephalitis in northern Italy

Tick-borne encephalitis (TBE) is caused by a flavivirus that infects animals including humans. In Europe, the TBE virus circulates enzootically in natural foci among ticks and rodent hosts. The abundance of ticks depends on the abundance of rodent hosts, which in turn depends on the availability of food resources, such as tree seeds. Trees can exhibit large inter-annual fluctuations in seed production (masting), which influences the abundance of rodents the following year, and the abundance of nymphal ticks two years later. Thus, the biology of this system predicts a 2-year time lag between masting and the incidence of tick-borne diseases such as TBE. As airborne pollen abundance is related to masting, we investigated whether inter-annual variation in pollen load could be directly correlated with inter-annual variation in the incidence of TBE in human populations with a 2-year time lag. We focused our study on the province of Trento (northern Italy), where 206 TBE cases were notified between 1992 and 2020. We tested the relationship between TBE incidence and pollen load collected from 1989 to 2020 for 7 different tree species common in our study area. Through univariate analysis we found that the pollen quantities recorded two years prior for two tree species, hop-hornbeam (Ostrya carpinifolia) and downy oak (Quercus pubescens), were positively correlated with TBE emergence (R2 = 0.2) while a multivariate model with both tree species better explained the variation in annual TBE incidence (R2 = 0.34). To the best of our knowledge, this is the first attempt at quantifying the correlation between pollen quantities and the incidence of TBE in human populations. As pollen loads are collected by widespread aerobiological networks using standardized procedures, our study could be easily replicated to test their potential as early warning system for TBE and other tick-borne diseases.

TBE in Denmark

Since the 1950s, tick-borne encephalitis (TBE) has been known to be endemic in Denmark but only on the island of Bornholm. Bornholm is situated east of mainland Denmark, south of Sweden (Figure 3) and has a different fauna and flora from the rest of Denmark. Bornholm has about 45,000 inhabitants, but about 500,000 tourists visit the island every year. Freundt carried out a serosurvey during 1958–1962 and found TBE antibodies in 1.4% of blood donors and 30% of woodworkers on Bornholm but no antibodies in subjects living in mainland Denmark. In 1963, Freundt found that 8 of 12 patients admitted to the hospital with acute meningoencephalitis of unknown etiology during 1951–1960 had antibodies to tick-borne encephalitis (TBEV). In 2000, TBE was rediscovered on Bornholm, where a retrospective study covering the period 1994–2002 (7 years) identified 14 TBE cases; 2 cases were tourists and 12 were inhabitants of Bornholm, giving an incidence of 3.81 per 100,000 inhabitants. At least 5 patients (37.7%) got permanent sequelae. In addition, 32 forest workers on Bornholm were tested in 2000, and 20% had IgG antibodies but never symptoms. This is similar to the finding of Freundt in 1960. It was concluded that the data did not provide evidence of an increase in incidence of TBE. Ticks (Ixodes ricinus) from Bornholm were investigated for TBEV in 2000 and 2% were found to be infected. Since 2001 an average of 2.5 (range 1–8) TBE cases per year have been reported in Bornholm (Figure 1).