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The emergence of tick-borne encephalitis (TBE) in Europe marked several significant milestones. The discovery of TBE in Czechoslovakia in 1948, with Gallia and Krejčí simultaneously isolating the TBE virus (TBEV) from human samples for the first time in Europe outside the Soviet Union, was pivotal. Subsequent TBEV isolation from ticks suggested the viral transmission via this vector. In 1951, the outbreak in Rožňava in Slovakia (Czechoslovakia) revealed an unexpected mode of transmission, unpasteurized milk from a local dairy, challenging existing understanding. Investigations exposed illicit practices of mixing cow's milk with goat's milk for economic gains. Laboratory research confirmed the outbreak was caused by TBEV, which was substantiated by serological analyses. This was the first and largest documented alimentary TBE outbreak in history. In this review, we delve into both published sources and unpublished archival data, offering a comprehensive understanding of these historic accomplishments and shedding light on these pivotal moments., (Copyright © 2024 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

Before the advent of a vaccine, 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, I describe my personal recollections of the development of a highly purified TBE vaccine in the late 1970s, to which I contributed as a young post-doctoral scientist mentored by Christian Kunz (then director of the Institute of Virology at the Medical Faculty, University of Vienna) in a collaboration with the Austrian biopharmaceutical company Immuno. Low reactogenicity of the newly developed vaccine was a prerequisite 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 a dramatic reduction of the incidence of TBE in Austria, which is outstanding in Europe and referred to as an Austrian success story of immunoprophylaxis., (© 2023. The Author(s).)

The tick-borne encephalitis (TBE) virus has been confirmed by molecular analysis in the Caucasus region for the first time. The virus obtained from a tick Ixodes ricinus ex Caspian green lizard belongs to the Zausaev strain of the Siberian subtype (not to a strain of the European subtype highly distributed in the territories adjacent to the Caucasus). This unusual record indicates the need to study the role of lizards in the circulation of natural focal infections.

Introduction: Tick-borne encephalitis (TBE) is rapidly spreading to new areas in many parts of Europe. While vaccination remains the most effective method of protection against the disease, vaccine uptake is low in many endemic countries., Areas Covered: We conducted a literature search of the MEDLINE database to identify articles published from 2018 to 2023 that evaluated the immunogenicity and effectiveness of TBE vaccines, particularly Encepur, when booster doses were administered up to 10 years apart. We searched PubMed with the MeSH terms 'Encephalitis, Tick-Borne/prevention and control' and 'Vaccination' for articles published in the English language., Expert Opinion: Long-term immunogenicity data for Encepur and real-world data on vaccine effectiveness and breakthrough infections following the two European TBE vaccines, Encepur and FSME-Immun, have shown that extending the booster interval from 3-5 years to 10 years does not negatively impact protection against TBE, regardless of age. Such extension not only streamlines the vaccination schedules but may also increase vaccine uptake and compliance among those living in endemic regions.

Tick-borne encephalitis (TBE) is an infectious illness of the central nervous system caused by the TBE virus, which is commonly transmitted through a tick-bite. TBE is endemic in Europe and mid-Asia. In this study, we report a case of a 36-year-old woman, living in Northeastern Poland, with a history of double corneal transplantation and post-transplant immunosuppressive therapy who was admitted to hospital because of progressive weakness, acute headache, nausea, vertigo, vomiting, and fever. The patient was diagnosed with TBE. However, the diagnosis was challenging as the initial serological tests for antibodies against the TBE virus were negative. We want to raise the awareness among the clinicians that the course of TBE is often unpredictable and that it tends to be more severe in immunocompromised individuals.. Delayed production of antibodies against TBE virus, which might inhibit the diagnosis of the disease, is observed in some immunocompromised patients., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2023 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

Background: Tick-borne encephalitis (TBE) is an infectious disease caused by the tick-borne encephalitis virus (TBEV) in patients with symptoms of central nervous system (CNS) inflammation. More than 25 European countries have one or more TBE-endemic areas. Although two TBE vaccines, FSME-IMMUN® and Encepur®, are commonly used in Europe, there are no published reviews of the real-world effectiveness of TBE vaccines in Europe or elsewhere., Methods: We searched PubMed for TBE vaccine effectiveness (VE) articles and extracted information on country, study design, study period, study population, number of TBEV-infected cases, number of participants, and VE against TBEV infection and outcomes., Results: We identified 13 studies, conducted in Austria, the Czech Republic, Latvia, Germany, and Switzerland, published in 2003-2023. One study was a cohort investigation of a milk-borne outbreak. In the other studies, 11 (91.7%) used the screening method and two (16.7%) used a case-control design (one study used both). TBE vaccines were highly effective (VE estimates >92%) against TBEV infection in all age groups. Vaccines were also highly protective against mild infections (i.e., infections in patients without symptoms of CNS inflammation), and against infections resulting in TBE and hospitalization. Vaccines were also highly protective against the most serious outcomes such as hospitalization greater than 12 days. Product-specific VE estimates were also high, though limited data were available. Studies in Austria, the Czech Republic, Latvia, and Switzerland estimated that TBE vaccines prevented >1,000 TBE cases a year, avoiding many hospitalizations and deaths, in these countries combined., Conclusions: Published VE studies demonstrate a high real-world effectiveness of the commercially available TBE vaccines in Europe. Although cases averted have been estimated in only four countries, TBE vaccination prevents thousands of cases in Europe each year. To prevent life-threatening TBE, TBE vaccine uptake and compliance with the vaccination schedule should be increased in residents of, and travelers to, TBE-endemic countries in Europe., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Frederick J. Angulo reports a relationship with Pfizer Inc that includes: employment and equity or stocks. Pingping Zhang reports a relationship with Pfizer Inc that includes: employment and equity or stocks. Kate Halsby reports a relationship with Pfizer Inc that includes: employment and equity or stocks. Patrick Kelly reports a relationship with Pfizer Inc that includes: employment and equity or stocks. Andreas Pilz reports a relationship with Pfizer Inc that includes: employment and equity or stocks. Harish Madhava reports a relationship with Pfizer Inc that includes: employment and equity or stocks. Jennifer C. Moisi reports a relationship with Pfizer Inc that includes: employment and equity or stocks. Luis Jodar reports a relationship with Pfizer Inc that includes: employment and equity or stocks., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Tick-borne encephalitis virus (TBEV) causes tick-borne encephalitis (TBE), affecting human health in Europe and Asia. Reports on canine clinical cases of TBE are rare, although dogs are used as sentinels for assessing human health risks. The first canine clinical TBE case in Greece is reported in this case report. The dog had a history of tick infestation and displayed neurological symptoms, particularly tetraparesis, neck hyperalgesia, and a sudden behavior change. Serum samples were obtained and examined in a commercial ELISA to detect anti-TBEV specific IgG and IgM antibodies. The dog tested seropositive for both IgG and IgM, and based on its history and compatible clinical signs, the diagnosis of TBE infection was reached. The prognosis was initially poor, and treatment included the administration of fluids, corticosteroids, and antibiotics, followed by physical therapy. After a 10-day hospitalization, the dog had a much better prognosis. This case highlights that TBEV does emerge in new locations, increasing human and animal infection risk. Veterinarians should include TBE in their differential diagnosis of canine patients with a history of tick infestations, progressive neurological symptoms, and abnormal behavior., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interests., (Copyright © 2023. Published by Elsevier GmbH.)

Tick-borne encephalitis (TBE) is a viral tick-borne infection occurring in many parts of Europe and Asia as described in this review. Increasing TBE case numbers have been reported over recent decades. In Denmark the infection is rare (1-14 annual cases). The rise in TBE in Denmark is mainly driven by microfoci outside of Bornholm, primarily North Zealand. Clinical illness has a bi-phasic presentation: "summer-flu" which may be followed by a neuroinfection. No specific treatment exists, and mortality is less-than 1%. A considerable percentage of patients may experience neurological sequelae. TBE is preventable through vaccination., (Published under Open Access CC-BY-NC-BD 4.0. https://creativecommons.org/licenses/by-nc-nd/4.0/.)

BackgroundTick-borne encephalitis (TBE) is a disease which can lead to severe neurological symptoms, caused by the TBE virus (TBEV). The natural transmission cycle occurs in foci and involves ticks as vectors and several key hosts that act as reservoirs and amplifiers of the infection spread. Recently, the incidence of TBE in Europe has been rising in both endemic and new regions.AimIn this study we want to provide comprehensive understanding of the main ecological and environmental factors that affect TBE spread across Europe.MethodsWe searched available literature on covariates linked with the circulation of TBEV in Europe. We then assessed the best predictors for TBE incidence in 11 European countries by means of statistical regression, using data on human infections provided by the European Surveillance System (TESSy), averaged between 2017 and 2021.ResultsWe retrieved data from 62 full-text articles and identified 31 different covariates associated with TBE occurrence. Finally, we selected eight variables from the best model, including factors linked to vegetation cover, climate, and the presence of tick hosts.DiscussionThe existing literature is heterogeneous, both in study design and covariate types. Here, we summarised and statistically validated the covariates affecting the variability of TBEV across Europe. The analysis of the factors enhancing disease emergence is a fundamental step towards the identification of potential hotspots of viral circulation. Hence, our results can support modelling efforts to estimate the risk of TBEV infections and help decision-makers implement surveillance and prevention campaigns.

Background: 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., Methods: 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)]., Results: 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., Conclusion: 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., Competing Interests: D.Z. declares a research grant within the Research Collaboration to Rīga Stradinš University (employer) from Pfizer Vaccines. Z.F. declares editorial support for the manuscript by Pfizer. L.R.H., C.B., P.Z., F.J.A., W.E., A.G., J.C.M., and L.J. are employees of Pfizer Inc. and hold stock and stock options in Pfizer Inc. The other authors have no conflicts of interest to disclose., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Vector-borne zoonotic diseases are a concerning issue in Europe. Lyme disease and tick-borne encephalitis virus (TBEV) have been reported in several countries with a large impact on public health; other emerging pathogens, such as Rickettsiales, and mosquito-borne flaviviruses have been increasingly reported. All these pathogens are linked to wild ungulates playing roles as tick feeders, spreaders, and sentinels for pathogen circulation. This study evaluated the prevalence of TBEV, Borrelia burgdorferi sensu lato, Rickettsia spp., Ehrlichia spp., and Coxiella spp. by biomolecular screening of blood samples and ticks collected from wild ungulates. Ungulates were also screened by ELISA and virus neutralization tests for flaviviral antibody detection., Results: A total of 274 blood samples were collected from several wild ungulate species, as well as 406 Ixodes ricinus, which were feeding on them. Blood samples tested positive for B. burgdorferi s.l. (1.1%; 0-2.3%) and Rickettsia spp. (1.1%; 0-2.3%) and showed an overall flaviviral seroprevalence of 30.6% (22.1-39.2%): 26.1% (17.9-34.3%) for TBEV, 3.6% (0.1-7.1%) for Usutu virus and 0.9% (0-2.7%) for West Nile virus. Ticks were pooled when possible and yielded 331 tick samples that tested positive for B. burgdorferi s.l. (8.8%; 5.8-11.8%), Rickettsia spp. (26.6%; 21.8-31.2%) and Neoehrlichia mikurensis (1.2%; 0-2.4%). TBEV and Coxiella spp. were not detected in either blood or tick samples., Conclusions: This research highlighted a high prevalence of several tick-borne zoonotic pathogens and high seroprevalence for flaviviruses in both hilly and alpine areas. For the first time, an alpine chamois tested positive for anti-TBEV antibodies. Ungulate species are of particular interest due to their sentinel role in flavivirus circulation and their indirect role in tick-borne diseases and maintenance as Ixodes feeders and spreaders., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Tick-borne encephalitis (TBE) is one of the most severe human tick-borne diseases in Europe. It is caused by the tick-borne encephalitis virus (TBEV), which is transmitted to humans mainly via bites of Ixodes ricinus or I. persulcatus ticks. The geographical distribution and abundance of I. ricinus is expanding in Sweden as has the number of reported human TBE cases. In addition to tick bites, alimentary TBEV infection has also been reported after consumption of unpasteurized dairy products. So far, no alimentary TBEV infection has been reported in Sweden, but knowledge about its prevalence in Swedish ruminants is scarce. In the present study, a total of 122 bulk tank milk samples and 304 individual milk samples (including 8 colostrum samples) were collected from dairy farms (n = 102) in Sweden. All samples were analysed for the presence of TBEV antibodies by ELISA test and immunoblotting. Participating farmers received a questionnaire about milk production, pasteurization, tick prophylaxis used on animals, tick-borne diseases, and TBE vaccination status. We detected specific anti-TBEV antibodies, i.e., either positive (>126 Vienna Units per ml, VIEU/ml) or borderline (63-126 VIEU/ml) in bulk tank milk from 20 of the 102 farms. Individual milk samples (including colostrum samples) from these 20 farms were therefore collected for further analysis. Our results revealed important information for detection of emerging TBE risk areas. Factors such as consumption of unpasteurized milk, limited use of tick prophylaxis on animals and a moderate coverage of human TBE vaccination, may be risk factors for alimentary TBEV infection in Sweden., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Tick-borne encephalitis (TBE) is a potentially fatal disease common in much of Europe and Asia. There is no specific therapy for the treatment of TBE patients. However, several efforts are being made to develop small molecules that specifically interfere with the life cycle of TBE virus. In particular, recently various nucleoside analogues that can inhibit the viral replicase, such as the RNA-dependent RNA polymerase or viral methyltransferases, have been explored. In addition, human or chimeric (i.e., structural chimeras that combine mouse variable domains with human constant domains) monoclonal antibodies with promising potential for post-exposure prophylaxis or early therapy have been developed. This review summarizes the latest directions and experimental approaches that may be used to combat TBE in humans., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Tick-Borne Encephalitis (TBE) - Clinical and Therapeutical Aspects Abstract. Tick-borne encephalitis (TBE) is an acute inflammatory disease of the central nervous system transmitted by ticks and caused by the TBE virus, which is found in more and more parts of Europe and Asia. Only 2-30% of infections are symptomatic, and a biphasic course of fever is typical in the prodromal stage. Clinically-neurologically, 50% of cases develop meningitis, 40% meningoencephalitis, and 10% meningoencephalomyelitis. The latter is often associated with feared brainstem involvement. Encephalitis is characterized by impaired consciousness, fatigue, emotional lability, and neurocognitive deficits; myelitis is characterized by flaccid paralysis of the arms or legs. Simultaneous detection of TBEV-specific IgM and IgG antibodies in serum and a matching inflammatory CSF syndrome is required to confirm the diagnosis. Meningitis heals without sequelae; 80% of cases of encephalitis and only 20% of cases of myelitis recover completely. The overall lethality rate is 1%. Immunocompromised, elderly, and myelitic patients are at higher risk for severe disease progression and mortality. Because no specific antiviral therapy is available, active TBE vaccination remains the most important preventive measure for all persons 6 years of age and older residing in high-risk areas.

Tick-Borne Encephalitis - Viral Transmission and Considerations for Vaccination Abstract. Tick-Borne encephalitis virus (TBEV) is a flavivirus transmitted to humans primarily through the bite of infected Ixodes ticks. Infection with TBEV results in Tick-Borne Encephalitis (TBE), an acute disease of the Central Nervous System (CNS) that can lead to significant long-term sequalae. Over the last decades the geographic range of TBEV and the incidence of TBE have substantially increased. TBEV is now endemic through much of Central Europe, including parts of Germany, Austria, and Switzerland, and is recognized as an increasing public health problem. While there are no specific therapies for TBE, two vaccines are licensed and available in Europe, Encepur ® and FSME-Immun ® . Both are considered safe and effective. Following vaccination, the generation of virus-neutralizing antibodies is often considered an indicator of protection against disease. While recent evidence suggests that cell-mediated immune responses likely also play important roles in protection, cell-mediated immunity following infection and vaccination remains poorly characterized. As with many vaccines, the initial response to TBE vaccination is influenced by several factors. Here, we review how age, immunosuppression, adherence to recommended vaccination schedules, and the use of single vaccine type during priming may impact immunity following TBE vaccination. We further discuss vaccination coverage and disease prevention, as well as factors impacting individual vaccine uptake.

Horses and other equids can be infected with several viruses of the family Flaviviridae, belonging to the genus Flavivirus and Hepacivirus. This consensus statement focuses on viruses with known occurrence in Europe, with the objective to summarize the current literature and formulate clinically relevant evidence-based recommendations regarding clinical disease, diagnosis, treatment, and prevention. The viruses circulating in Europe include West Nile virus, tick-borne encephalitis virus, Usutu virus, Louping ill virus and the equine hepacivirus. West Nile virus and Usutu virus are mosquito-borne, while tick-borne encephalitis virus and Louping ill virus are tick-borne. The natural route of transmission for equine hepacivirus remains speculative. West Nile virus and tick-borne encephalitis virus can induce encephalitis in infected horses. In the British Isle, rare equine cases of encephalitis associated with Louping ill virus are reported. In contrast, equine hepacivirus infections are associated with mild acute hepatitis and possibly chronic hepatitis. Diagnosis of flavivirus infections is made primarily by serology, although cross-reactivity occurs. Virus neutralization testing is considered the gold standard to differentiate between flavivirus infections in horses. Hepacivirus infection is detected by serum or liver RT-PCR. No direct antiviral treatment against flavi- or hepacivirus infections in horses is currently available and thus, treatment is supportive. Three vaccines against West Nile virus are licensed in the European Union. Geographic expansion of flaviviruses pathogenic for equids should always be considered a realistic threat, and it would be beneficial if their detection was included in surveillance programs., (© 2022 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Health control measures instituted in 2020 to mitigate the COVID-19 pandemic decreased the case numbers of many infectious diseases across Europe. One notable exception was tick-borne encephalitis (TBE). In Austria, Germany, Switzerland, Lithuania, and the Czech Republic, the upturn was significantly higher compared to the average of the three years previously (P<0.05), with increases of 88%, 48%, 51%, 28%, and 18%, respectively. Six countries reported TBE incidences of ≥5 cases/100,000, defined as highly endemic by the World Health Organization (WHO). Possible factors contributing to this surge may include increased participation in outdoor activities in endemic regions and increased tick counts/tick activity. In highly endemic regions, the WHO recommends that vaccination be offered to all age groups, including children., (Copyright © 2022 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

Climate change has influenced the transmission of a wide range of vector-borne diseases in Europe, which is a pressing public health challenge for the coming decades. Numerous theories have been developed in order to explain how tick-borne diseases are associated with climate change. These theories include higher proliferation rates, extended transmission season, changes in ecological balances, and climate-related migration of vectors, reservoir hosts, or human populations. Changes of the epidemiological pattern have potentially catastrophic consequences, resulting in increasing prevalence of tick-borne diseases. Thus, investigation of the relationship between climate change and tick-borne diseases is critical. In this regard, climate models that predict the ticks' geographical distribution changes can be used as a predicting tool. The aim of this review is to provide the current evidence regarding the contribution of the climatic changes to Lyme borreliosis (LB) disease and tick-borne encephalitis (TBE) and to present how computational models will advance our understanding of the relationship between climate change and tick-borne diseases in Europe.

Background: Tick-borne encephalitis (TBE) is an infectious disease of the central nervous system caused by the TBE virus (TBEV), which is usually transmitted by a tick-bite, with increasing incidence in northeastern Europe and eastern Asia during the past decade. Ocular involvement has not been described in the literature to date., Case Presentation: A 58-year-old patient presented to the emergency department with occipital headaches and poor balance for 5 days. He reported a tick-bite 6 weeks before without erythema migrans followed by a flu-like syndrome. Serological testing was negative for Borreliosis and TBEV. At presentation, he was febrile with neck stiffness and signs of ataxia. Three days later, he presented unilateral visual loss in his right eye. Examination revealed non granulomatous anterior uveitis, vitreous inflammation, and retinal haemorrhages at the posterior pole without macular oedema or papillitis. Polymerase chain reaction (PCR) of the cerebrospinal fluid returned negative for all Herpes family viruses. No clinical evidence of other infection nor malignancy was identified. A seroconversion of the TBEV- immunoglobulin titres was observed 2 weeks later while the serum antibodies for Borrelia were still not detected. Magnetic resonance imaging was unremarkable. We concluded to the diagnosis of TBE-related uveitis. Under supportive treatment, there was complete resolution of the neurological symptoms and the intraocular inflammation without sequelae within the following weeks., Conclusions: We describe a new association of TBEV with uveitis. In view of the growing number of TBE cases and the potential severity of the disease we aim at heightening awareness to achieve prompt recognition, prevention, and treatment., (© 2021. The Author(s).)

Tick-borne encephalitis (TBE) is a febrile illness caused by tick-borne encephalitis virus (TBEV), frequently manifesting as inflammation of the central nervous system. TBEV is a typical arbovirus, i.e., belongs to a group of viruses transmitted by blood-sucking arthropods. Taxonomically, TBEV is a member of the genus Flavivirus, family Flaviviridae. The disease is endemic in North Eurasia, from western Europe to East Asia. The virus occurs in natural foci of the disease all over Czechia, where it is transmitted predominantly by the castor bean tick (Ixodes ricinus). This infection has a potential to cause significant long-term disability affecting the quality of the patients life. Vaccine is available; however, vaccination coverage in Czechia is still low (around 30% of the total population). Lately, attention has been focused on new possibilities for early diagnosis and specific treatment, which so far has only been symptomatic or empirical.

Background: Tick-borne encephalitis (TBE) constitutes a public health concern in Europe. Certain coastal municipalities in southern Norway are considered TBE risk areas and in the last two years, there have been increasing numbers of TBE cases. Since the majority of infections are claimed to be asymptomatic, the aim of the current study was to assess the seroprevalence of antibodies to tick-borne encephalitis virus (TBEV) among unvaccinated adults living in a TBE endemic area in Norway., Methods: One thousand one hundred and twenty-three blood donors living in Vestfold and Telemark county were included and associated sera were analysed for TBEV IgG antibodies. Information regarding tick bites, previous flavivirus exposure and knowledge regarding TBE and TBE prevention were obtained through a questionnaire., Results: Fifty-eight samples were reactive by ELISA, of which 21 (36.2%) were confirmed by a TBEV-specific serum neutralization test. Of the 21 blood donors with neutralizing TBEV antibodies detected, 17 reported previous TBE vaccination. Thus, only four blood donors (0.4%) had TBEV neutralizing antibodies consistent with previously undergone TBEV infection. Regarding TBE awareness, half of the blood donors were familiar with TBE, but only 35% were aware of a preventive TBE vaccine., Conclusions: Our study indicates low prevalence of subclinical TBEV infections among blood donors living in Vestfold and Telemark county and there is a lack of awareness among general public.

Tick-borne encephalitis virus (TBEV) is an important central nervous system (CNS) infection in Europe and Asia. It is a flavivirus in the tick-borne group. Effective vaccines against TBE are available in the affected countries. However, diagnosing TBE is challenging due to cross-reactive antibodies between different viruses of the genus Flavivirus , family Flaviviridae. Differentiation between infection-induced and vaccine-induced antibodies can be difficult and in many cases impossible, due to the increasing vaccination rate against TBEV. We present a new approach to detect antibodies against the TBEV nonstructural protein 1 (NS1) as a diagnostic marker, which is exclusively indicative for virus replication in natural infection, on the basis of an enzyme-linked immunosorbent assay (ELISA). A total of 188 anonymous serum samples from the National Consultant Laboratory for TBEV were included in our study. The assay was validated according to the European Laboratory Norm DIN EN ISO 15189 for diagnostic use. The ELISA for the detection of TBEV NS1 specific IgG class antibodies has demonstrated a sensitivity of >94% and a specificity of >93% in broadly cross-reacting sera from patients with vaccinations against flaviviral diseases and single or multiple flavivirus infections, respectively. The detection of anti-NS1 antibodies is feasible and facilitates reliable differentiation between different flavivirus infections, TBEV infection, and TBE vaccination., (Copyright © 2020 American Society for Microbiology.)

Ticks are hematophagous arthropods that transmit a number of pathogens while feeding. Among these is tick-borne encephalitis virus (TBEV), a flavivirus transmitted by Ixodes ricinus ticks in the temperate zone of Europe. The infection results in febrile illness progressing to encephalitis and meningitis with a possibility of fatality or long-term neurological sequelae. The composition of tick saliva plays an essential role in the initial virus transmission during tick feeding. Ticks secrete a diverse range of salivary proteins to modulate the host response, such as lipocalins to control the itch and inflammatory response, and both proteases and protease inhibitors to prevent blood coagulation. Here, the effect of viral infection of adult females of Ixodes ricinus was studied with the goal of determining how the virus alters the tick sialome to modulate host tissue response at the site of infection. Uninfected ticks or those infected with TBEV were fed on mice and removed and dissected one- and 3-h post-attachment. RNA from the salivary glands of these ticks, as well as from unfed ticks, was extracted and subjected to next-generation sequencing to determine the expression of key secreted proteins at each timepoint. Genes showing statistically significant up- or down-regulation between infected and control ticks were selected and compared to published literature to ascertain their function. From this, the effect of tick viral infection on the modulation of the tick-host interface was determined. Infected ticks were found to differentially express a number of uncategorized genes, proteases, Kunitz-type serine protease inhibitors, cytotoxins, and lipocalins at different timepoints. These virus-induced changes to the tick sialome may play a significant role in facilitating virus transmission during the early stages of tick feeding., (Copyright © 2020 Hart, Ribeiro, Kazimirova and Thangamani.)

The risk of tick-borne encephalitis (TBE) among U.S. military service members and beneficiaries residing in or traveling to Europe has not been assessed since the 1990s. The primary objective of this study was to assess the current risk of TBE in this population. Records of reportable medical events, inpatient and outpatient care, and laboratory test results were searched for TBE cases between 2006 and 2018. There were 8 individuals who met the case definition for TBE over the 13-year interval; 7 cases occurred during 2017 or 2018. Outpatient records did not identify any additional verified cases of TBE but revealed a large number of misclassified diagnoses. The risk of TBE among U.S. military service members and beneficiaries is low but may have increased in recent years. Military members and their dependents residing in Europe or Asia generally have a risk for TBE similar to that of other residents of the host nation. Additionally, there may be locations or activities that place certain individuals or units at increased risk for TBE, thus warranting additional control measures such as active surveillance, enhanced personal protective measures, and vaccination.

In Europe, Lyme borreliosis (LB) and tick-borne encephalitis (TBE) are the two vector-borne diseases with the largest impact on human health. Based on data on the density of host-seeking Ixodes ricinus ticks and pathogen prevalence and using a variety of environmental data, we have created an acarological risk model for a region where both diseases are endemic (Czech Republic-South Bohemia and Germany-Lower Bavaria, Upper Palatinate). The data on tick density were acquired by flagging 50 sampling sites three times in a single season. Prevalence of the causative agents of LB and TBE was determined. Data on environmental variables (e.g., altitude, vegetation cover, NDVI, land surface temperature) were obtained from various sources and processed using geographical information systems. Generalized linear models were used to estimate tick density, probability of tick infection, and density of infected ticks for the whole area. A significantly higher incidence of human TBE cases was recorded in South Bohemia compared to Bavarian regions, which correlated with a lower tick density in Bavaria. However, the differences in pathogen prevalence rates were not significant. The model outputs were made available to the public in the form of risk maps, indicating the distribution of tick-borne disease risk in space.

Viral meningitis may be present not only in adults but also in children. It constitutes a significant public health problem in child population. The clinical manifestation of the disease in children varies depending on the age of the child, the causative agent or the way of acquiring the infection. Thanks to the widespread availability of vaccinations, the epidemiology of central nervous system infections is changing. The methods of diagnosing and determining the causative factor have also changed. Sensitive and rapid molecular methods such as PCR tests are being used more frequently. The article contains an overview of the most common causes, clinical signs and symptoms, complications and principles of diagnosing and treating viral meningitis in children. Currently, Enteroviruses are at the top positions among the causes of sporadic and epidemic meningitis in children living in various geographic regions of the world. In European countries, the common cause of viral meningitis and/or encephalitis is tick-borne encephalitis virus. The severity of the clinical course of TBE is inversely proportional to the age of the affected children. In USA, sub-Saharan Africa and recently in southern Europe epidemic West Nile Virus (Flaviviridae family) central system infections were reported. Herpes simplex encephalitis is uncommon in children and has a severe course (especially in vertically infected infants). The mortality rate in Herpes simplex encephalitis is 20- 25% despite acyclovir treatment., (© 2019 MEDPRESS.)

Tick-borne encephalitis virus (TBEV) is the most common arbovirus transmitted by ticks in Europe. Approximately 10,000 cases of tick-borne encephalitis (TBE) are reported annually in Europe and Russia. Although TBE is endemic in parts of China, information regarding its incidence is limited. TBEV is closely related to Powassan virus (POWV), another tick-borne flavivirus that is a rare cause of encephalitis in North America and Russia; TBEV and POWV can cross-react in serologic tests. Before 2000, two cases of TBE in North American travelers to Europe were reported. State health officials or clinicians send specimens from patients with unexplained encephalitis to CDC as part of routine surveillance and diagnostic testing. CDC recently reviewed all 2000-2009 laboratory records to identify cases of TBE among U.S. travelers; the five cases identified are summarized in this report. All five cases had TBEV or POWV immunoglobulin M (IgM) antibodies in serum and were confirmed as acute TBE cases by plaque-reduction neutralization tests against both viruses. All four patients who had traveled to Europe or Russia had biphasic illnesses (a common feature of TBE) and made nearly complete recoveries. The fifth patient, the first reported case of TBE in a U.S. traveler to China, had a monophasic illness with severe encephalitis and neurologic sequelae. Health-care providers should be aware of TBE, should counsel travelers about measures to reduce exposure to tick bites, and should consider the diagnosis of TBE in travelers returning from TBE-endemic countries with meningitis or encephalitis.

The importance of tick-borne encephalitis (TBE) and Lyme borreliosis-the main European tick-borne diseases-is steadily growing. This fact is due to many different factors including climate changes. However, across Europe many other human pathogenic viruses, bacteria, and parasites are found in ticks. This article gives an overview of tick-borne human pathogenic viruses present in Europe as well as those considered nonpathogenic. It also deals with the various species of vector-competent ticks. Among these ticks, viruses from 6 families encompassing 8 genera and 35 species are found,whereby the families Flaviviridae, Bunyaviridae, and Reoviridae with the genera flavivirus, nairovirus, and orbivirus are the most prevalent. Because of their special importance Omsk hemorrhagic fever, louping-ill disease, tick-borne encephalitis, and Crimean-Congo hemorrhagic fever are discussed in detail. Although West Nile virus is mainly transmitted to man by mosquitoes, it is discussed in detail, because West Nile fever has become a good example for a new and rapidly spreading vector-borne disease in the USA and for a recurrent one in Europe. Secondly, besides the mosquito-bird cycle an interesting tick--bird cycle is emerging. The overview clearly demonstrates that in Europe (particularly in Germany) tick-borne viruses, with the exception of TBE, constitute an extremely ignored research subject. This lack of attention is in contrast to their importance and results in a lack of necessary scientific data.

Tick-borne encephalitis (TBE) is caused by a Flavivirus and transmitted by ticks. It is known in dogs for nearly 30 years and the number of TBE cases is increasing. In addition to fever, cerebrocortical, thalamic, and brainstem symptoms occur simultaneously. Not all TBE infections in dogs lead to clinical signs but peracute/lethal as well as subacute and chronic courses have been reported. TBE is a seasonal disease, depending on climate related tick activity. Infected ticks are spreading the virus over central Europe with a tendency to expand to new endemic areas in western Europe.

Flaviviruses are among the most important emerging viruses known to man. Most are arboviruses (arthropod-borne) being transmitted by mosquitoes or ticks. They derived from a common ancestor 10-20000 years ago and are evolving rapidly to fill new ecological niches. Many are spreading to new geographical areas and causing increased numbers of infections. Traditionally, three clinical syndromes are recognized: fever-arthralgia-rash, viral haemorrhagic fever, and neurological disease, though for some flaviviruses the disease pattern is changing. Dengue, the most important flavivirus, is transmitted between humans by Aedes mosquitoes. Recent work is elucidating the pathogenesis of its most severe form, dengue haemorrhagic fever. Yellow fever, which has epidemiological similarities to dengue, was under control in the mid-20th century, but is once again increasing. Japanese encephalitis virus is numerically the most important cause of epidemic encephalitis; its geographical area is expanding despite the availability of vaccines. Other mosquito-borne neurotropic flaviviruses with clinical and epidemiological similarities are found across the globe. These include St Louis encephalitis virus, Murray Valley encephalitis virus, and West Nile virus, which recently reached the Americas for the first time. In cooler northern climates ticks are more important vectors. Tick-borne encephalitis virus occurs across large parts of Eastern Europe and the Commonwealth of Independent states. The tick-borne haemorrhagic flaviviruses, Omsk haemorrhagic fever and Kyasanur Forrest disease are localized in small areas.