Tick-borne Encephalitis Research Articles

Impacts of long-term climate change on human health: a global scoping review

Abstract Introduction Research output on climate change and human health is growing rapidly. This can make it difficult to find and use relevant information to develop public health action. Methods We present a global scoping review of the rapidly growing quantitative research output on long-term climate change and human health. We searched Scopus, Embase, and PubMed for quantitative, English language literature published between January 2000 and June 2021 that referenced climate change and human health in titles, abstracts, or keywords. Results From 36,956 publications we identified 754 relevant studies. Europe, the Americas, and the Western Pacific were studied much more often than other WHO regions. Research on temperature and vectors accounted for 70% of all included publications. Malaria, diarrheal diseases, and cardiovascular diseases were the most studied specific health outcomes. We found very few studies on non-communicable diseases in low- and middle-income countries. Retrospective publications (153) showed effects of climate change are already occurring worldwide. Most studies on tick-borne encephalitis, malaria, and lower respiratory infections associated with air pollution found impacts caused by climate change have increased. The strongest attribution of climate change was found for heat-related impacts. In prospective publications (626) diarrheal diseases, and impacts associated with heat and chemical air pollution were most consistently projected to increase. Future vector-borne disease impacts were projected to be highly location specific. Some studies demonstrated adaptation can effectively reduce impacts, while noting that capacity to adapt differs greatly between population groups. Conclusions Our findings underline climate change impacts are diverse and complex. Future research should prioritize the relatively understudied regions most vulnerable to climate change, such as Africa, and impacts beyond those related to temperature and vector-borne diseases.

Preparation and Construction of Chimeric Humanized Broadly Reactive Antibody 10H10 to Protein E of Tick-Borne Encephalitis Virus.

A full-length humanized chimeric antibody 10H10ch that specifically interacts with the surface glycoprotein E of flaviviruses was obtained. To construct it, we used variable fragments of the heavy and light chains of the monoclonal antibody 10H10 that form the active center of the antibody and a fragment of the constant part of the heavy chain of the human IgG1 antibody. The resulting full-length chimeric humanized antibody 10H10ch specifically interacted with the E protein of flaviviruses pathogenic to humans, such as tick-borne encephalitis, Zika, West Nile, and dengue viruses. An immunochemical assessment of the interaction constants of the 10H10ch antibody with a panel of native and recombinant flavivirus antigens by ELISA and biolayer interferometry showed that the dissociation constant (Kd) of the chimeric antibody is in the nanomolar region and is comparable to that of the high-affinity mouse monoclonal antibody 10H10. The possibility of using the resulting chimeric humanized antibody 10H10ch for the diagnosis, prevention, and treatment of various flavivirus infections is discussed.

Prevalence and Genetic Diversity of Deer Tick Virus (Powassan Virus, Lineage II) in Ixodes scapularis Ticks in Five Habitats at a Nature Reserve in Southern Maine, United States.

Deer tick virus (DTV), also known as Powassan virus lineage II, is a rising health concern due to increased recognition as a cause of human encephalitis. Since European tick-borne encephalitis virus persists in nature in enzootic foci (i.e., higher prevalence rates in small pockets in nature), we sought to determine whether DTV is also focally maintained in relation to habitat type, to better understand factors leading to human risk of exposure. From 2018 to 2021, questing Ixodes scapularis ticks were collected from five habitats at the Wells National Estuarine Research Reserve (WNERR) in Wells, ME: forest with invasive vegetation in the understory, edge, shrub, forest with native vegetation in the understory, and open field. Deer tick virus prevalence was greater in adult ticks (2.0%) than in nymphs (0.5%). Deer tick virus prevalence in adult ticks collected from forest with invasive vegetation was 3.2% compared to 0 to 1.7% in other habitat types. A hot spot analysis revealed a higher number of infected adults collected per hour on one of the transects located in forest with invasive vegetation. Phylogenetic analysis of 37 full-length DTV genomes sequenced in this study revealed four major clades from the WNERR, and there was high genetic diversity within each transect, suggesting frequent, short-range dispersal between habitats. Analysis of DTV sequences from other New England counties and states also indicated long-distance dispersal to and/or from the WNERR. This study provides preliminary evidence that DTV is focal and that the risk of encountering DTV-infected ticks in forest with invasive vegetation may be greater than in other habitat types.

What makes patients tick? Vaccine preferences against tick-borne encephalitis in four European countries

BackgroundWe explored vaccine motivation and preferences for tick-borne encephalitis (TBE) vaccine attributes among participants in TBE-endemic countries in Europe.MethodsAn online survey was conducted among the general public in Austria, Germany, Switzerland, and Sweden. Participants were ≥ 18 years old, open to receiving vaccines, and living in, or regularly traveling to, TBE-endemic regions in the aforementioned countries. Participants were asked about their general vaccine knowledge and motivations for vaccination, before rating the importance of TBE vaccine attributes, such as efficacy, safety, dosing schedule, and booster interval. Thereafter, participants were shown three hypothetical TBE vaccine profiles with different combinations of attributes. Assuming equal efficacy and safety, participants were asked to select their preferred profile from 12 screens as part of a discrete-choice conjoint analysis. Utility scores were calculated to show the importance of each attribute. Data are presented for the overall survey group and by age and gender, using t-tests to compare means.ResultsFor 73% of participants (n = 1003/1379), self-protection was among the top three reasons to get vaccinated. Disease severity, protection of children or family, and advice or recommendation from a doctor/healthcare professional (HCP) were top three reasons for over half of participants. The majority (58–69%) agreed or strongly agreed that they trust their doctor/HCP on the subject of vaccines, they rely on their doctor/HCP’s vaccine knowledge, and they prefer their doctor/HCP to make recommendations on which vaccines they or their families should take. Efficacy and safety were the most important standalone TBE vaccine attributes; however, among TBE vaccine profiles including 3-, 5- and 10-year booster intervals, the 10-year booster interval was the most influential attribute level when choosing a preferred vaccine profile (utility score: 0.58 [standard error: 0.01]). Differences in motivators and preferences were observed between age and gender subgroups.ConclusionThe high level of doctor/HCP reliance highlights the key role doctors/HCPs play in influencing vaccine decision-making. Booster interval was the biggest driver of choice when selecting a hypothetical TBE vaccine profile, with the strongest preference for a 10-year booster interval. These findings could be used to inform TBE vaccination recommendations and in the further development of TBE vaccines.

Does the Vaccination against Tick-Borne Encephalitis Offer Good Value for Money for Incidence Rates below the WHO Threshold for Endemicity? A Case Study for Germany.

A closed-cohort Markov model was developed to estimate the cost-effectiveness of TBE vaccination. We compared primary vaccination applied to the whole population (aged above 1 year) and to a subpopulation aged between 60 and 85 years to a scenario without vaccination. Since TBE incidence is often underestimated, we included under-ascertained TBE cases and non-CNS TBE infections. Germany was used as a case study due to the availability of detailed incidence data. Our incidence threshold analysis showed that TBE vaccination offers good value for money well below the WHO threshold in most of the analyzed scenarios. Our results support a recommendation for TBE vaccination even in settings with low numbers of reported cases, especially for older patients. Furthermore, this analysis identified major research gaps regarding the costs, utilities, and clinical progression of TBE.

Analysis of the zoonotic tick-borne encephalitis virus (TBEV) in raw milk and dairy products in mountain pastures of the Lombardy region, Italy.

Over the last few decades, tick-borne encephalitis (TBE) has become a growing public health problem in Europe. The tick-borne encephalitis virus (TBEV) is a zoonotic virus that affects the central nervous system (CNS). TBEV has been detected in 27 European countries, and the rise in TBE cases is mainly due to environmental and ecological factors, and factors that increase the risk of human exposure to infected ticks. The infection via the alimentary route is the second most common means of TBEV transmission to humans. Raw milk from infected goats, sheep, or cows has been identified as a source of human food-borne infections. This study aims to gather new information on the prevalence of tick-borne encephalitis virus (TBEV) in raw goat's and cow's milk and related raw products in the Lombard Alps (Italy). This is important due to the close proximity of Lombardy to the Triveneto region, where TBE is endemic, and southern Switzerland, where numerous TBEV-positive mammals have been found. Throughout 2023, a passive monitoring plan was implemented on samples delivered for TBEV analyses from the Alpine pastures. In total, 248 specimens including raw milk, raw milk cheese, and butter were tested. This is the first monitoring of food at risk of TBEV transmission in a non-endemic region with evidence of TBEV circulation. Despite testing a wide range of dairy products, no sample tested positive for RNA-TBEV by real-time RT-PCR. Preliminary results suggest that raw milk and raw dairy products do not pose a significant risk of TBEV transmission to humans in the territory of Lombardy.

Changes in the genome of tick-borne encephalitis virus during cultivation

The tick-borne encephalitis virus (TBEV) of the Siberian genotype was previously isolated from the brain of a deceased person. TBEV variants obtained at passages 3 and 8 on SPEV cells were inoculated into the brains of white mice for subsequent passages. Full-genome sequences of all virus variants were analyzed by high-throughput sequencing. The analysis showed the presence of 41 point nucleotide substitutions, which were mainly localized in the genes of non-structural proteins NS3 and NS5 of TBEV. In the deduced virus protein sequences, 12 amino acid substitutions were identified. After three passages through mouse brains, reverse nucleotide and amino acid substitutions were detected. Most of them were mapped in the NS5 protein gene, where 5 new nucleotide substitutions also appeared. At the same time, there was an increase in the length of the 3′-untranslated region (3′-UTR) of the viral genome by 306 nucleotides. The Y3 and Y2 3’-UTR elements were found to contain imperfect L and R repeats, which probably associated with inhibition of the activity of cellular XRN1 RNase and thus involved in the formation of sfRNA1 and sfRNA2. For all TBEV variants, high levels of infectious virus were detected both in cell culture and in the brain of white mice. The revealed changes in the genome that occur during successive passages of TBEV are most likely due to the significant genetic variability of the virus, which ensures its efficient reproduction in different hosts and active circulation in nature.

Epidemiological and clinical characteristics of cases and detection of pathogens’ markers of tick-borne infections in the Tomsk region

BACKGROUND: Among the spectrum of the tick-borne infections, Lyme borreliosis and tick-borne encephalitis are most often recorded in the Tomsk region, however it is obviously that possible range of the pathogens is not limited to these ones. AIM: To make epidemiological and clinical characteristics of cases and detect frequencies of pathogen’s markers of tick-borne infections among adult patients applying serological and molecular genetic techniques in the Tomsk region during 2020–2023. METHODS: A single-center prospective sample study was conducted applying a comprehensive approach in peripheral blood specimens obtained from 197 patients with suspected tick-borne infections hospitalized during 2020–2023. To verify the diagnoses of tick-borne encephalitis or Lyme borreliosis, specific immunoglobulins of classes M and G to the antigens of virus of tick-borne encephalitis and Borrelia burgdorferi s.l. were determined in paired blood serum samples applying enzyme-linked immunosorbent assay. Additionally, the polymerase chain reaction was used to detect genetic markers of virus of tick-borne encephalitis, B. burgdorferi s.l., B. miyamotoi, Rickettsia spp., Coxiella burnetii, and Francisella tularensis. Epidemiological surveillance data of incidence rates of tick-borne infections obtained from official reports were analyzed as well. MS Office Excel 2010 software was used to calculate frequency morbidity measures. RESULTS: We verified the final diagnosis of tick-borne encephalitis in 52 (26.4%) patients, Lyme borreliosis in 116 (58.9%) patients, co-infection of tick-borne encephalitis and Lyme borreliosis 15 (7.6%) patients, hard tick relapsing fever caused by B. miyamotoi in 8 (4.1%) patients, coinfection of Q fever caused by C. burnetii with tick-borne encephalitis or Lyme borreliosis in 4 (2.0%) patients, and coinfection of tularemia with tick-borne encephalitis or Lyme borreliosis in 2 (1.0%) cases. We identified markers of tick-borne encephalitis and Lyme borreliosis pathogens by polymerase chain reaction in 3.6% and 4.1% of the patients. Most number of individuals with tick bites, and the highest incidence rates of Lyme borreliosis and tick-borne encephalitis were recorded in the suburbs of Tomsk. The age groups of 40–59 years, and elderly people 60 years and older were predominated among the patients. CONCLUSIONS: It was found out that, in addition to Lyme borreliosis and tick-borne encephalitis, there were such tick-borne infections as tick relapsing fever, Q fever, and tularemia in the Tomsk region in the 2020–2023 period.

Features of subset composition and functional activity of blood lymphocytes in tick-borne infections of different etiologies

Aim. To perform a comparative assessment of subset composition and functional activity of peripheral blood lymphocytes in patients with tick-borne encephalitis (TBE) and ixodid tick-borne borreliosis (ITBB) in the acute phase of the disease.Materials and methods. The study involved 22 patients with febrile and meningeal TBE, 15 patients with ITBB with and without erythema, and 11 healthy controls. Subset composition of blood lymphocytes was determined by flow cytometry. The blast transformation assay was applied to assess lymphocyte proliferation. Cytokine-producing activity of cells was studied in 24-hour incubated mononuclear cell cultures. Cytokine concentrations (interleukin (IL)-2, IL-4, IL-10, interferon (IFN)γ) were determined in the supernatants by the enzyme-linked immunosorbent assay (ELISA).Results. Patients with TBE demonstrated an increase in the proportion of helper – inducer T-cells, a pronounced decrease in the proportion and absolute count of cytotoxic T cells, and low T lymphocyte count compared to the control values. The study in ITBB patients revealed an increase in the helper – inducer T-cell count and the proportion of NK-cells, a decrease in the cytotoxic T cell count, and the T lymphocyte count comparable to normal values. The most significant decrease in the levels of phytohemagglutinin-induced lymphocyte proliferation was found in patients with TBE. Patients of both groups showed a decrease in IL-2 secretion in the mononuclear cell culture, a rise in IL-4 and IL-10 production, and IFNγ production levels comparable to control values.Conclusion. The study of TBE patients revealed relative lymphocytopenia with changes in the subset composition of lymphocytes characterized by an increase in the proportion of helper – inducer T-cells and a decrease in the absolute cytotoxic T lymphocyte count. Patients with ITBB demonstrated an increase in the proportion of NK-cells and a more pronounced imbalance in the T-helper / cytotoxic T lymphocyte ratio. Changes in the functional phenotype of lymphocytes, regardless of the etiology of tick-borne infection, were characterized by reduced proliferative reserve, low IL-2 secretion, increased IL-4 and IL-10 production, and depressed reactivity of lymphocytes with respect to IFNγ secretion.

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.

Glycerophospholipid remodeling is critical for orthoflavivirus infection.

Flavivirus infection is tightly connected to host lipid metabolism. Here, we performed shotgun lipidomics of cells infected with neurotropic Zika, West Nile, and tick-borne encephalitis virus, as well as dengue and yellow fever virus. Early in infection specific lipids accumulate, e.g., neutral lipids in Zika and some lysophospholipids in all infections. Ceramide levels increase following infection with viruses that cause a cytopathic effect. In addition, fatty acid desaturation as well as glycerophospholipid metabolism are significantly altered. Importantly, depletion of enzymes involved in phosphatidylserine metabolism as well as phosphatidylinositol biosynthesis reduce orthoflavivirus titers and cytopathic effects while inhibition of fatty acid monounsaturation only rescues from virus-induced cell death. Interestingly, interfering with ceramide synthesis has opposing effects on virus replication and cytotoxicity depending on the targeted enzyme. Thus, lipid remodeling by orthoflaviviruses includes distinct changes but also common patterns shared by several viruses that are needed for efficient infection and replication.

Recombinant Analogue of Envelope Glycoprotein Domain III of the Tick-Borne Encephalitis Virus and its Application for the Differential Diagnosis of Flavivirus Infections

Recombinant Analogue of Envelope Glycoprotein Domain III of the Tick-Borne Encephalitis Virus and its Application for the Differential Diagnosis of Flavivirus Infections

Selection Pressure Profile Suggests Species Criteria among Tick-Borne Orthoflaviviruses.

Orthoflaviviruses are arthropod-borne viruses that are transmitted by mosquitoes or ticks and cause a range of significant human diseases. Among the most important tick-borne orthoflaviviruses (TBFVs) is tick-borne encephalitis virus (TBEV), which is endemic in Eurasia, and Powassan virus, which is endemic in Asia and North America. There is a significant controversy regarding species assignment in the tick-borne encephalitis virus complex due to the complex phylogenetic, serological, ecological, and pathogenetic properties of viruses. Comparing the rate of non-synonymous to synonymous substitutions (dN/dS) over the course of tick-borne orthoflavivirus diversification suggests that there is a very strong stabilizing selection (Nei-Gojobori dN/dS < 0.1) among tick-borne orthoflaviviruses that differ by less than 13.5% amino acid/21.4% nucleotide sequences, and discretely more rapid accumulation of non-synonymous substitutions (dN/dS > 0.13) among more divergent viruses that belong to distinct species. This pattern was similarly observed in genome regions encoding structural (E) and non-structural (NS3) proteins. Below this distance threshold, viruses appear fit and strongly tied to their ecological niche, whereas above the threshold, a greater degree of adaptation appears necessary. This species criterion suggests that all subtypes of TBEV, all related ovine/caprine encephalomyelitis viruses, and Omsk hemorrhagic fever virus (OHFV) together correspond to a single species. Within this species, viruses make up 11 subtypes that are reliably segregated by a 10% nucleotide distance cut-off suggested earlier for TBEV. The same 10% subtype cut-off suggests that Powassan virus includes two subtypes, Powassan and Deer Tick virus.

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.

Autoantibodies neutralizing type I IFNs underlie severe tick-borne encephalitis in ∼10% of patients.

Tick-borne encephalitis (TBE) virus (TBEV) is transmitted to humans via tick bites. Infection is benign in >90% of the cases but can cause mild (<5%), moderate (<4%), or severe (<1%) encephalitis. We show here that ∼10% of patients hospitalized for severe TBE in cohorts from Austria, Czech Republic, and France carry auto-Abs neutralizing IFN-α2, -β, and/or -ω at the onset of disease, contrasting with only ∼1% of patients with moderate and mild TBE. These auto-Abs were found in two of eight patients who died and none of 13 with silent infection. The odds ratios (OR) for severe TBE in individuals with these auto-Abs relative to those without them in the general population were 4.9 (95% CI: 1.5-15.9, P < 0.0001) for the neutralization of only 100 pg/ml IFN-α2 and/or -ω, and 20.8 (95% CI: 4.5-97.4, P < 0.0001) for the neutralization of 10 ng/ml IFN-α2 and -ω. Auto-Abs neutralizing type I IFNs accounted for ∼10% of severe TBE cases in these three European cohorts.

Clinical Evaluation of the VirClia IgM/IgG Chemiluminescence Tests for the Diagnosis of Tick-Borne Encephalitis in an Endemic Part of Norway.

The aim of this study was to evaluate the clinical usefulness of VirClia IgM/IgG single-assay chemiluminescence tests for the diagnosis of tick-borne encephalitis (TBE) in an endemic part of Norway. Patients hospitalized at Vestfold or Telemark Hospitals with suspected infection in the central nervous system (CNS) in the period between May 2021 and December 2023 were included, with 85 TBE cases identified. The VirClia IgM assay was positive in the initial serum sample in 75/85 cases, giving a sensitivity of 88.2% (95% CI, 79.4-94.2). The ReaScan TBE IgM rapid test was positive in 80/85 cases, with an estimated sensitivity of 94.1% (95% CI, 86.8-98.1). Vaccine breakthrough infections were the predominant cause of non-reactive IgM cases. The calculated specificity for the VirClia IgM was 95.8% (95% CI, 92.5-98.0). In conclusion, the sensitivity of the VirClia IgM was non-inferior to the ReaScan TBE IgM rapid test. However, isolated IgM reactive results must be interpreted with caution, since false-reactive results occur.

Ticks and Tick-Borne Pathogens in Popular Recreational Areas in Tallinn, Estonia: The Underestimated Risk of Tick-Borne Diseases.

This study reveals a significant presence of ticks and tick-borne pathogens in urban recreational areas of Tallinn, Estonia. During the period of May-June 2018, 815 Ixodes ticks were collected from an area of 11,200 m2 using the flagging method. Tick density reached up to 18.8 ticks per 100 m2, indicating a high concentration of ticks in these urban green spaces. Pathogen analysis demonstrated that 34% of the collected ticks were infected with at least one pathogen. Specifically, Borrelia burgdorferi s.l., the causative agent of Lyme borreliosis, was detected in 17.4% of the ticks; Rickettsia spp. was detected in 13.5%; Neoehrlichia mikurensis was detected in 5.5%; Borrelia miyamotoi was detected in 2.6%; and Anaplasma phagocytophilum and tick-borne encephalitis virus were detected in 0.5% each. These findings indicate that the prevalence and abundance of ticks and tick-borne pathogens in these urban environments are comparable to or even exceed those observed in natural endemic areas. Given the increasing incidence of Lyme borreliosis in Central and Northern Europe, the risk of tick bites and subsequent infection in urban recreational sites should not be underestimated. Public health measures, including enhanced awareness and precautionary information, are essential to mitigate the risk of tick-borne diseases in these urban settings.

Immune Response after Vaccination against Tick-Borne Encephalitis Virus (TBEV) in Horses.

(1) Background: Horses infected by a tick-borne encephalitis virus (TBEV) can develop clinically apparent infections. In humans, vaccination is the most effective preventive measure, while a vaccine is not available for horses. The objective of this study was to describe the immune response in horses after a TBEV vaccination with a human vaccine. (2) Materials and Methods: Seven healthy horses were randomised to a treatment or a control group in a stratified fashion based on TBEV-IgG concentrations on day -4. The treatment group (n = 4) was intramuscularly vaccinated using an inactivated human TBEV vaccine on days 0 and 28; the control group (n = 3) did not receive an injection. A clinical examination and blood sampling were performed on day -4, 0, 2, 4, 6, 8, 10, 14, 28, 30, 32, 34, 36, 38, 43, 56, 84, and 373. A linear mixed model analysis was used to compare IgG and IgM concentrations, neutralising antibody (nAb) titres, leucocyte count, serum amyloid A (SAA), and fibrinogen and globulin concentrations between the groups and time points. (3) Results: The clinical examination was normal in all horses at all time points. There were no significant changes in SAA, globulin, and fibrinogen concentrations and leucocyte count between the groups or time points (all p > 0.05). There was no significant increase in IgG, IgM, or nAb titres in the control group over time (all p > 0.05). In the vaccination group, there was a significant increase in IgG concentration and nAb titres after the second vaccination (p < 0.0001). There was no significant increase in IgM antibodies after the TBEV vaccination (all p > 0.05). One horse in the vaccination group had an IgM concentration above the laboratory reference on day 10. (4) Conclusions: The human TBEV vaccine did not have side effects when used in healthy horses in this study. A significant rise in TBEV-specific IgG antibodies and nAbs after the second vaccination was observed. However, IgG and nAb titres have been shown to decrease within 1 year after vaccination. The results of this study indicate that a vaccination with a human vaccine only induces a mild rise in IgM antibodies and only in previously naive horses. With no significant changes to inflammatory parameters in the vaccinated horses, it remains unclear whether vaccination with the human vaccine leads to protective immunity.

Seropositivity to tick-borne pathogens in nature management workers in the Netherlands

The incidence of tick-borne infections other than Lyme borreliosis and tick-borne encephalitis is rising in Europe, including the Netherlands. Nature management workers, being highly exposed to ticks, serve as valuable sentinels for seroprevalence studies on tick-borne pathogens (TBPs). This study assessed nature management workers’ seropositivity to TBPs including Anaplasma phagocytophilum, Babesia divergens, B. microti, Borrelia burgdorferi s.l., Rickettsia conorii and R. typhi in the Netherlands. In addition, the study examined coexposure to multiple TBPs and identified risk factors for B. burgdorferi s.l.- and A. phagocytophilum-seropositivity.The study included 525 nature management workers who donated serum and completed a questionnaire. Sera were analysed for exposure to A. phagocytophilum, B. divergens, B. microti, R. conorii and R. typhi using immunofluorescence assays. For B. burgdorferi s.l. antibody detection, the recommended two-tier testing strategy was used. Risk factor analysis was performed using logistic regression modelling.Seropositivity was 30.9 % for B. burgdorferi s.l.; 16.4 % for A. phagocytophilum; 6.5 % for R. conorii; 2.3 % for R. typhi; 4.2 % for B. divergens; and 0.4 % for B. microti. Almost half (49.3 %) of the participants demonstrated seropositivity for one or more pathogens. Risk factors for B. burgdorferi s.l.-seropositivity included being male, increasing age and tick bite frequency. For A. phagocytophilum-seropositivity, increasing age and working in North Holland province were significant risk factors.This study illustrates the exposure to TBPs in the Netherlands, emphasizing the need for ongoing vigilance and international collaborations to better understand and address the growing threat of TBPs in regions with demonstrated environmental TBP circulation.