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Epidemiology anamnesis of human cases of TBEV in Slovakia (source: www.uvzsr.sk (accessed on 23 December 2021)). The dashed line represents a linear trendline for the alimentary infections.
Source publication
Tick-borne encephalitis virus (TBEV) causes serious the neurological disease, tick-borne encephalitis (TBE). TBEV can be transmitted to humans by ticks as well as by the alimentary route, which is mediated through the consumption of raw milk products from infected ruminants such as sheep, goats, and cows. The alimentary route of TBEV was recognized...
Citations
... As the demand for raw milk grows, so does the potential for alimentary transmission of TBEV (Friker et al., 2020;Ličková et al., 2022). ...
Tick‐borne encephalitis virus (TBEV) is a significant cause of flaviviral infections affecting the human central nervous system, primarily transmitted through tick bites and the consumption of unpasteurized milk. This study aimed to assess the prevalence of TBEV and identify new natural foci of TBEV in livestock milk. In this cross‐sectional study, unpasteurized milk samples were collected from livestock reared on farms and analysed for the presence and subtyping of TBEV using nested reverse transcription‐polymerase chain reaction , alongside the detection of anti‐TBEV total IgG antibodies using ELISA. The findings revealed that the highest prevalence of TBEV was observed in goat and sheep milk combined, whereas no TBEV was detected in cow milk samples. All identified strains were of the Siberian subtype. Moreover, the highest prevalence of anti‐TBEV antibodies was detected in sheep milk. These results uncover new foci of TBEV in Iran, underscoring the importance of thermal processing (pasteurization) of milk prior to consumption to mitigate the risk of TBEV infection.
... In Western Europe, only the European subtype (TBEV-Eu) naturally circulates between the tick Ixodes ricinus (reservoir species and vector) and forest rodents (known competent hosts). TBE causes severe human neuroinfection with a fatal outcome in 0.5 to 2% of cases [3]. TBEV is mainly transmitted to humans via bites from infected ticks. ...
... TBEV is mainly transmitted to humans via bites from infected ticks. However, food-borne transmission has also been regularly reported in Eastern and Central Europe after consumption of unpasteurized dairy products from infected domestic ungulates [3]. Food-borne outbreaks mainly occur in clusters [4][5][6][7][8][9][10][11][12]. ...
... Seroprevalence did not increase with age. In all cells, the [1][2][3] year-old category (n = 91) showed high seroprevalence, greater than 45%, revealing recent and intense viral circulation (Fig. 1b). According to generalized linear mixed model (GLMM) results, the probability of an individual being TBEV seropositive did not vary significantly according to age category. ...
Background
Tick-borne encephalitis (TBE) is a severe human neuroinfection caused by TBE virus (TBEV). TBEV is transmitted by tick bites and by the consumption of unpasteurized dairy products from infected asymptomatic ruminants. In France, several food-borne transmission events have been reported since 2020, raising the question of the level of exposure of domestic ungulates to TBEV. In this study, our objectives were (i) to estimate TBEV seroprevalence and quantify antibodies titres in cattle in the historical endemic area of TBEV in France using the micro virus neutralisation test (MNT) and (ii) to compare the performance of two veterinary cELISA kits with MNT for detecting anti-TBEV antibodies in cattle in various epidemiological contexts. A total of 344 cattle sera from four grid cells of 100 km² in Alsace-Lorraine (endemic region) and 84 from western France, assumed to be TBEV-free, were investigated.
Results
In Alsace-Lorraine, cattle were exposed to the virus with an overall estimated seroprevalence of 57.6% (95% CI: 52.1–62.8%, n = 344), varying locally from 29.9% (95% CI: 21.0–40.0%) to 92.1% (95% CI: 84.5–96.8%). Seroprevalence did not increase with age, with one- to three-year-old cattle being as highly exposed as older ones, suggesting a short-life duration of antibodies. The proportion of sera with MNT titres lower than 1:40 per grid cell decreased with increased seroprevalence. Both cELISA kits showed high specificity (> 90%) and low sensitivity (less than 78.1%) compared with MNT. Sensitivity was lower for sera with neutralising antibodies titres below 1:40, suggesting that sensitivity of these tests varied with local virus circulation intensity.
Conclusions
Our results highlight that cattle were highly exposed to TBEV. Screening strategy and serological tests should be carefully chosen according to the purpose of the serological study and with regard to the limitations of each method.
... Infection with TBEV in humans occurs after the bite of a tick carrying the virus. However, in addition to direct transmission, TBEV can also be transmitted in a food-borne way such as through raw milk [64], if the animal was infected after a bite. The main vectors of TBEV are Dermacentor reticulatus, Ixodes persulcatus, and Ixodes ricinus ticks. ...
Neuroinfections rank among the top ten leading causes of child mortality globally, even in high-income countries. The crucial determinants for successful treatment lie in the timing and swiftness of diagnosis. Although viruses constitute the majority of infectious neuropathologies, diagnosing and treating viral neuroinfections remains challenging. Despite technological advancements, the etiology of the disease remains undetermined in over half of cases. The identification of the pathogen becomes more difficult when the infection is caused by atypical pathogens or multiple pathogens simultaneously. Furthermore, the modern surge in global passenger traffic has led to an increase in cases of infections caused by pathogens not endemic to local areas. This review aims to systematize and summarize information on neuroinvasive viral pathogens, encompassing their geographic distribution and transmission routes. Emphasis is placed on rare pathogens and cases involving atypical pathogens, aiming to offer a comprehensive and structured catalog of viral agents with neurovirulence potential.
... Although the exact mechanism of TBEV transmission through the alimentary route is not yet clearly understood, the virulence of the virus may be influenced by the digestion of dairy products in the gastrointestinal tract. In particular, studies have shown that experimentally infected goats excrete TBEV up to 8 days post-infection (dpi) and exhibit TBEV infection with the virus detectable in their small intestines following oral infection (10,13,14). Usually, after ingestion, milk reaches the duodenum within a few minutes and after 1.5-2 h, it empties from the stomach (15). ...
Tick-borne flaviviruses (TBFs) are transmitted to humans through milk and tick bites. Although a case of possible mother-to-child transmission of tick-borne encephalitis virus (TBEV) through breast milk has been reported, this route has not been confirmed in experimental models. Therefore, in this study, using type I interferon receptor-deficient A129 mice infected with Langat virus (LGTV), we aimed to demonstrate the presence of infectious virus in the milk and mammary glands of infected mice. Our results showed viral RNA of LGTV in the pup’s stomach milk clots (SMCs) and blood, indicating that the virus can be transmitted from dam to pup through breast milk. In addition, we observed that LGTV infection causes tissue lesions in the mammary gland, and viral particles were present in mammary gland epithelial cells. Furthermore, we found that milk from infected mice could infect adult mice via the intragastric route, which has a milder infection process, longer infection time, and a lower rate of weight loss than other modes of infection. Specifically, we developed a nano-luciferase-LGTV reporter virus system to monitor the dynamics of different infection routes and observed dam-to-pup infection using in vivo bioluminescence imaging. This study provides comprehensive evidence to support breast milk transmission of TBF in mice and has helped provide useful data for studying TBF transmission routes.
IMPORTANCE
To date, no experimental models have confirmed mother-to-child transmission of tick-borne flavivirus (TBF) through breastfeeding. In this study, we used a mouse model to demonstrate the presence of infectious viruses in mouse breast milk and mammary gland epithelial cells. Our results showed that pups could become infected through the gastrointestinal route by suckling milk, and the infection dynamics could be monitored using a reporter virus system during breastfeeding in vivo. We believe our findings have provided substantial evidence to understand the underlying mechanism of breast milk transmission of TBF in mice, which has important implications for understanding and preventing TBF transmission in humans.
... Several TBEV foodborne outbreaks were reported in the EU, and TBEV infections have surged in the EU within the last decade [3]. For example, TBEV was detected in 5% of cow milk samples in Norway [11], and a case in Slovakia originated from unpasteurized cheese consumption [12]. However, based on systematic review and meta-analysis of European data, most human cases from consuming raw milk products are associated with goat milk [13,14]. ...
Tick-borne virus detection in livestock and slaughterhouse animals has recently surged in the United States and Europe. Although cases of patients with tick-borne illnesses have been reported in Korea, food contamination from tick-borne viruses has yet to be investigated. Therefore, this study investigated severe fever with thrombocytopenia syndrome virus (SFTSV), tick-borne encephalitis virus (TBEV), and Crimean–Congo hemorrhagic fever virus (CCHFV) prevalence in meat and dairy products. A total of 628 products were collected from a Korean retail market during 2021–2022, including 195 beef, 130 goats, 90 lambs, 61 pork, 50 chicken, and 38 commercial cheese samples. In addition, 64 raw cow milk samples were collected from a ranch in Anseong-si, Gyeonggi-do, from 2021 to 2022. Real-time reverse transcription-polymerase chain reaction (RT-PCR), nested reverse transcription polymerase chain reaction (RT-nPCR), virus cultivation, and sequence analysis were conducted. SFTSV was detected in 1.53% (3/195) beef and 0.76% (1/130) goat meat samples with a low Ct value titer from 33.18 to 38.60. In contrast, SFTSV was neither detected in lamb, pork, chicken, raw milk, or cheese samples nor were TBEV and CCHFV detected in any of the tested samples. Although no existing cases or studies have indicated SFTSV transmittance through food, this study confirmed SFTSV genotype B RNA in SFTSV-positive meat samples. Therefore, monitoring for and evaluating SFTSV-contaminated meat products must be investigated in future studies.
... The geographical distribution of the TBEV subtypes mimics the geographical distribution of the main vectors, the sheep tick Ixodes ricinus for the TBEV-Eur subtype and the taiga tick I. persulcatus for the TBEV-Sib and the TBEV-FE subtypes, but mixing of subtypes in the two vector species occurs [4]. Although TBEV is mainly transmitted to humans via tick bites, consumption of unpasteurised milk and milk products has also been reported as a source of infection [5][6][7]. The reservoir hosts of the virus are the ticks themselves and small mammals (e.g. ...
Background
In Sweden, information on seroprevalence of tick-borne encephalitis virus (TBEV) in the population, including vaccination coverage and infection, is scattered. This is largely due to the absence of a national tick-borne encephalitis (TBE) vaccination registry, scarcity of previous serological studies and use of serological methods not distinguishing between antibodies induced by vaccination and infection. Furthermore, the number of notified TBE cases in Sweden has continued to increase in recent years despite increased vaccination.
Aim
The aim was to estimate the TBEV seroprevalence in Sweden.
Methods
In 2018 and 2019, 2,700 serum samples from blood donors in nine Swedish regions were analysed using a serological method that can distinguish antibodies induced by vaccination from antibodies elicited by infection. The regions were chosen to reflect differences in notified TBE incidence.
Results
The overall seroprevalence varied from 9.7% (95% confidence interval (CI): 6.6–13.6%) to 64.0% (95% CI: 58.3–69.4%) between regions. The proportion of vaccinated individuals ranged from 8.7% (95% CI: 5.8–12.6) to 57.0% (95% CI: 51.2–62.6) and of infected from 1.0% (95% CI: 0.2–3.0) to 7.0% (95% CI: 4.5–10.7). Thus, more than 160,000 and 1,600,000 individuals could have been infected by TBEV and vaccinated against TBE, respectively. The mean manifestation index was 3.1%.
Conclusion
A difference was observed between low- and high-incidence TBE regions, on the overall TBEV seroprevalence and when separated into vaccinated and infected individuals. The estimated incidence and manifestation index argue that a large proportion of TBEV infections are not diagnosed.
... The European subtype TBEV-Eu, the most common one, is mainly associated with the biphasic form of TBE which has no chronic forms and presents symptoms with severe neurological sequelae in up to 10% of human cases and a fatality rate ranging from 1% to 2% [1]. Transmission to humans usually occurs after a tick bite, although food-borne infections after consumption of unpasteurised milk and dairy products from infected animals have been reported [4]. ...
Background
Tick-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.
Aim
In this study we want to provide comprehensive understanding of the main ecological and environmental factors that affect TBE spread across Europe.
Methods
We 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.
Results
We 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.
Discussion
The 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.
... Humans are incidental and dead-end hosts infected mainly through the bites of hard ticks. Another route of TBEV transmission may be the ingestion of unpasteurized milk or dairy products from infected animals [5]. In this article, we discuss the characteristics of TBEV, its structure, and the phylogenetic relationship of the circulating strains. ...
... It is estimated that approximately 1% of all TBEV infections in humans are transmitted by the alimentary route [52], and such infections have been reported in at least 10 European countries, with the highest numbers in Slovakia, Hungary, Czechia, and Poland. In Croatia, Germany, and Slovenia, single cases of TBE infections by the alimentary route have been reported [5]. ...
... Single cases of TBE transmitted by other routes have also been reported: aerosol infections among laboratory personnel [53], blood transfusions [54], and organ transplantation [55]. Transmission from an infected mother to her baby through breast milk is also suspected [5,56]. An example of a fatal TBEV infection following organ transplantation involved three patients who received organs from a single donor (two received a kidney and one received a liver). ...
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.
... Humans and domestic mammals, including dogs, goats, sheep, and cows, may be contaminated by tick bites. Besides tick bites, humans can be infected by the alimentary route via unpasteurized milk or milk products from animal origin (for reviews, see [67,68]). donor if available; in deceased donors, it is recommended to discard the organs, except in case of vital emergency for the recipient for which a benefit-risk evaluation must be performed. If organs are transplanted, a specific follow-up of the recipient is required [62]. ...
... Humans and domestic mammals, including dogs, goats, sheep, and cows, may be contaminated by tick bites. Besides tick bites, humans can be infected by the alimentary route via unpasteurized milk or milk products from animal origin (for reviews, see [67,68]). Data on the transmission of TBEV by products of human origin are scarce [68]. In 1989, Wahlberg et al. [69] reported one case of the transmission of TBEV by blood transfusion to two recipients in Finland (year not mentioned, but between 1959 and 1987). ...
Diseases caused by arboviruses are on the increase worldwide. In addition to arthropod bites, most arboviruses can be transmitted via accessory routes. Products of human origin (labile blood products, solid organs, hematopoietic stem cells, tissues) present a risk of contamination for the recipient if the donation is made when the donor is viremic. Mainland France and its overseas territories are exposed to a complex array of imported and endemic arboviruses, which differ according to their respective location. This narrative review describes the risks of acquiring certain arboviral diseases from human products, mainly solid organs and hematopoietic stem cells, in the French context. The main risks considered in this study are infections by West Nile virus, dengue virus, and tick-borne encephalitis virus. The ancillary risks represented by Usutu virus infection, chikungunya, and Zika are also addressed more briefly. For each disease, the guidelines issued by the French High Council of Public Health, which is responsible for mitigating the risks associated with products of human origin and for supporting public health policy decisions, are briefly outlined. This review highlights the need for a “One Health” approach and to standardize recommendations at the international level in areas with the same viral epidemiology.
... Humans and domestic mammals, including dogs, goats, sheep and cows, may be contaminated by tick bites. Besides tick bites, humans can be infected by alimentary route via unpasteurized milk or milk products from animal origin (for reviews, see [49,50]). Data on transmission of TBEV by products of human origin are scarce [50]. In 1989, Wahlberg et al. [51] reported in Finland one case of transmission of TBEV by blood transfusion to two recipients (year not mentioned between 1959 and 1987). ...
Diseases caused by arboviruses are on the increase worldwide. In addition to arthropod bites, most arboviruses can be transmitted via accessory routes. Products of human origin (labile blood products, solid organs, hematopoietic stem cells, tissues) present a risk of contamination for the recipient if the donation is made when the donor is viremic. This narrative review describes the risks of acquiring certain arboviral diseases from human products, mainly solid organs and hematopoietic stem cells, in the French context. Mainland France and its overseas territories are exposed to a complex array of imported and endemic arboviruses, which differ according to their respective location. The main risks considered in this study are infections by West Nile virus, dengue virus and tick-borne encephalitis virus. The ancillary risks represented by Usutu virus infection, chikungunya and Zika are also addressed more briefly. For each disease, the guidelines issued by the French High Council of Public Health, which is responsible for issuing guidelines to mitigate the risks associated with products of human origin and for supporting public health policy decisions, are briefly outlined. The aim of this review is also to contribute to the standardization of recommendations at international level in areas with the same viral epidemiology.
