Tick-borne encephalitis (TBE) is a viral disease endemic in Eurasia. The virus is mainly transmitted to humans via ticks and occasionally via the consumption of unpasteurized milk products. The European Centre for Disease Prevention and Control reported an increase in TBE incidence over the past years in Europe as well as the emergence of the disease in new areas. To better understand this phenomenon, we investigated the drivers of TBE emergence and increase in incidence in humans through an expert knowledge elicitation. We listed 59 possible drivers grouped in eight domains and elicited forty European experts to: (i) allocate a score per driver, (ii) weight this score within each domain, and (iii) weight the different domains and attribute an uncertainty level per domain. An overall weighted score per driver was calculated, and drivers with comparable scores were grouped into three terminal nodes using a regression tree analysis. The drivers with the highest scores were: (i) changes in human behavior/activities; (ii) changes in eating habits or consumer demand; (iii) changes in the landscape; (iv) influence of humidity on the survival and transmission of the pathogen; (v) difficulty to control reservoir(s) and/or vector(s); (vi) influence of temperature on virus survival and transmission; (vii) number of wildlife compartments/groups acting as reservoirs or amplifying hosts; (viii) increase of autochthonous wild mammals; and (ix) number of tick species vectors and their distribution. Our results support researchers in prioritizing studies targeting the most relevant drivers of emergence and increasing TBE incidence.
Tick-borne encephalitis (TBE) is an illness caused by tick-borne encephalitis virus (TBEV) infection which is often limited to a febrile illness, but may lead to very aggressive downstream neurological manifestations. The disease is prevalent in forested areas of Europe and northeastern Asia, and is typically caused by infection involving one of three TBEV subtypes, namely the European (TBEV-Eu), the Siberian (TBEV-Sib), or the Far Eastern (TBEV-FE) subtypes. In addition to the three main TBEV subtypes, two other subtypes; i.e., the Baikalian (TBEV-Bkl) and the Himalayan subtype (TBEV-Him), have been described recently. In Europe, TBEV-Eu infection usually results in only mild TBE associated with a mortality rate of <2%. TBEV-Sib infection also results in a generally mild TBE associated with a non-paralytic febrile form of encephalitis, although there is a tendency towards persistent TBE caused by chronic viral infection. TBE-FE infection is considered to induce the most severe forms of TBE. Importantly though, viral subtype is not the sole determinant of TBE severity; both mild and severe cases of TBE are in fact associated with infection by any of the subtypes. In keeping with this observation, the overall TBE mortality rate in Russia is ∼2%, in spite of the fact that TBEV-Sib and TBEV-FE subtypes appear to be inducers of more severe TBE than TBEV-Eu. On the other hand, TBEV-Sib and TBEV-FE subtype infections in Russia are associated with essentially unique forms of TBE rarely seen elsewhere if at all, such as the hemorrhagic and chronic (progressive) forms of the disease. For post-exposure prophylaxis and TBE treatment in Russia and Kazakhstan, a specific anti-TBEV immunoglobulin is currently used with well-documented efficacy, but the use of specific TBEV immunoglobulins has been discontinued in Europe due to concerns regarding antibody-enhanced disease in naïve individuals. Therefore, new treatments are essential. This review summarizes available data on the pathogenesis and clinical features of TBE, plus different vaccine preparations available in Europe and Russia. In addition, new treatment possibilities, including small molecule drugs and experimental immunotherapies are reviewed. The authors caution that their descriptions of approved or experimental therapies should not be considered to be recommendations for patient care.
- MeSH
- antivirové látky terapeutické užití MeSH
- fylogeneze MeSH
- klíšťata virologie MeSH
- klíšťová encefalitida farmakoterapie imunologie prevence a kontrola MeSH
- lidé MeSH
- myši MeSH
- virové vakcíny imunologie MeSH
- viry klíšťové encefalitidy imunologie patogenita MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Geografické názvy
- Evropa MeSH
- Rusko MeSH
Rat hepatitis E virus (HEV) is genetically only distantly related to hepeviruses found in other mammalian reservoirs and in humans. It was initially detected in Norway rats (Rattus norvegicus) from Germany, and subsequently in rats from Vietnam, the USA, Indonesia, China, Denmark and France. Here, we report on a molecular survey of Norway rats and Black rats (Rattus rattus) from 12 European countries for ratHEV and human pathogenic hepeviruses. RatHEV-specific real-time and conventional RT-PCR investigations revealed the presence of ratHEV in 63 of 508 (12.4%) rats at the majority of sites in 11 of 12 countries. In contrast, a real-time RT-PCR specific for human pathogenic HEV genotypes 1-4 and a nested broad-spectrum (NBS) RT-PCR with subsequent sequence determination did not detect any infections with these genotypes. Only in a single Norway rat from Belgium a rabbit HEV-like genotype 3 sequence was detected. Phylogenetic analysis indicated a clustering of all other novel Norway and Black rat-derived sequences with ratHEV sequences from Europe, the USA and a Black rat-derived sequence from Indonesia within the proposed ratHEV genotype 1. No difference in infection status was detected related to age, sex, rat species or density of human settlements and zoological gardens. In conclusion, our investigation shows a broad geographical distribution of ratHEV in Norway and Black rats from Europe and its presence in all settlement types investigated.
- MeSH
- divoká zvířata MeSH
- druhová specificita MeSH
- fylogeneze MeSH
- hepatitida E epidemiologie veterinární virologie MeSH
- hustota populace MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- rozšíření zvířat MeSH
- virus hepatitidy E klasifikace genetika izolace a purifikace MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Evropa epidemiologie MeSH
