scholarly journals Tick-Borne Encephalitis Virus: Seasonal and Annual Variation of Epidemiological Parameters Related to Nymph-to-Larva Transmission and Exposure of Small Mammals

Pathogens ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 518
Author(s):  
Laure Bournez ◽  
Gerald Umhang ◽  
Marie Moinet ◽  
Céline Richomme ◽  
Jean-Michel Demerson ◽  
...  
Keyword(s):  
Small Mammals ◽  
Temporal Variations ◽  
Encephalitis Virus ◽  
Myodes Glareolus ◽  
Mountain Forest ◽  
Annual Variations ◽  
Tick Borne Encephalitis ◽  
Tick Borne Encephalitis Virus ◽  
Over Time ◽  
Epidemiological Parameters

A greater knowledge of the ecology of the natural foci of tick-borne encephalitis virus (TBEV) is essential to better assess the temporal variations of the risk of tick-borne encephalitis for humans. To describe the seasonal and inter-annual variations of the TBEV-cycle and the epidemiological parameters related to TBEV nymph-to-larva transmission, exposure of small mammals to TBEV, and tick aggregation on small mammals, a longitudinal survey in ticks and small mammals was conducted over a 3-year period in a mountain forest in Alsace, eastern France. TBEV prevalence in questing nymphs was lower in 2013 than in 2012 and 2014, probably because small mammals (Myodes glareolus and Apodemus flavicollis) were more abundant in 2012, which reduced tick aggregation and co-feeding transmission between ticks. The prevalence of TBEV in questing nymphs was higher in autumn than spring. Despite these variations in prevalence, the density of infected questing nymphs was constant over time, leading to a constant risk for humans. The seroprevalence of small mammals was also constant over time, although the proportion of rodents infested with ticks varied between years and seasons. Our results draw attention to the importance of considering the complex relationship between small mammal densities, tick aggregation on small mammals, density of infected questing nymphs, and prevalence of infected nymphs in order to forecast the risk of TBEV for humans.

scholarly journals First detection of tick-borne encephalitis virus in Ixodes ricinus ticks and their rodent hosts in Moscow, Russia

2018 ◽  
Author(s):  
Marat Makenov ◽  
Lyudmila Karan ◽  
Natalia Shashina ◽  
Marina Akhmetshina ◽  
Olga Zhurenkova ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Ixodes Ricinus ◽  
Small Mammals ◽  
Encephalitis Virus ◽  
Myodes Glareolus ◽  
Gps Tracking ◽  
Bank Voles ◽  
Tick Borne Encephalitis ◽  
Two Samples ◽  
Tick Borne Encephalitis Virus

AbstractHere, we report the first confirmed autochthonous tick-borne encephalitis case diagnosed in Moscow in 2016 and describe the detection of Tick-borne encephalitis virus (TBEV) in ticks and small mammals in a Moscow park.The paper includes data from two patients who were bitten by TBEV-infected ticks within the Moscow city limits; one of these cases led to the development of the meningeal form of TBE. Both TBEV-infected ticks attacked patients in the same area. We collected ticks and trapped small mammals in this area in 2017. All samples were screened for the presence of pathogens causing tick-borne diseases by PCR. The TBEV-positive ticks and small mammals’ tissue samples were subjected to virus isolation. The sequencing of the complete polyprotein gene of the positive samples was performed.A total of 227 questing ticks were collected. TBEV was detected in five specimens of Ixodes ricinus. We trapped 44 small mammals, mainly bank voles (Myodes glareolus) and pygmy field mice (Apodemus uralensis). Two samples of brain tissue from bank voles yielded a positive signal in RT-PCR for TBEV. We obtained six virus isolates from the ticks and brain tissue of a bank vole. Complete genome sequencing showed that the obtained isolates belong to the European subtype and have low diversity with sequence identities as high as 99.9%. GPS tracking showed that the maximum distance between the exact locations where the TBEV-positive ticks were collected was 185 m. We assume that the forest park was free of TBEV and that the virus was recently introduced.

scholarly journals Disappearance of TBEV Circulation among Rodents in a Natural Focus in Alsace, Eastern France

Pathogens ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 930
Author(s):  
Laure Bournez ◽  
Gerald Umhang ◽  
Marie Moinet ◽  
Jean-Marc Boucher ◽  
Jean-Michel Demerson ◽  
...  
Keyword(s):  
Small Mammals ◽  
Meteorological Conditions ◽  
Myodes Glareolus ◽  
Mountain Forest ◽  
Apodemus Flavicollis ◽  
Natural Focus ◽  
Serum Samples ◽  
Tick Borne Encephalitis ◽  
Western Border ◽  
Tick Borne Encephalitis Virus

Tick-borne encephalitis virus (TBEV) depends mainly on a fragile mode of transmission, the co-feeding between infected nymphs and larvae on rodents, and thus persists under a limited set of biotic and abiotic conditions. If these conditions change, natural TBEV foci might be unstable over time. We conducted a longitudinal study over seven years in a mountain forest in Alsace, Eastern France, located at the western border of known TBEV distribution. The objectives were (i) to monitor the persistence of TBEV circulation between small mammals and ticks and (ii) to discuss the presence of TBEV circulation in relation to the synchronous activity of larvae and nymphs, to the densities of questing nymphs and small mammals, and to potential changes in meteorological conditions and deer densities. Small mammals were trapped five times per year from 2012 to 2018 to collect blood samples and record the presence of feeding ticks, and were then released. Questing nymphs were collected twice a year. Overall, 1344 different small mammals (Myodes glareolus and Apodemus flavicollis) were captured and 2031 serum samples were tested for the presence of antibodies against TBEV using an in-house ELISA. Seropositive rodents (2.1%) were only found from 2012 to 2015, suggesting that the virus disappeared afterwards. In parallel, we observed unusual variations in inter-annual nymph abundance and intra-annual larval activity that could be related to exceptional meteorological conditions. Changes in the densities of questing nymphs and deer associated with the natural stochastic variations in the frequency of contacts between rodents and infected ticks may have contributed to the endemic fadeout of TBEV on the study site. Further studies are needed to assess whether such events occur relatively frequently in the area, which could explain the low human incidence of TBE in Alsace and even in other areas of France.

Tick-Borne Encephalitis Virus Diversity in Ixodid Ticks and Small Mammals in South-Western Siberia, Russia

2016 ◽  
Vol 16 (8) ◽  
pp. 541-549 ◽  
Author(s):  
Valentina N. Bakhvalova ◽  
Galina S. Chicherina ◽  
Olga F. Potapova ◽  
Victor V. Panov ◽  
Victor V. Glupov ◽  
...  
Keyword(s):  
Small Mammals ◽  
Western Siberia ◽  
Encephalitis Virus ◽  
Ixodid Ticks ◽  
Virus Diversity ◽  
Tick Borne Encephalitis ◽  
Tick Borne Encephalitis Virus

TBE in South Korea

2021 ◽  
Author(s):  
Song Joon Young
Keyword(s):  
South Korea ◽  
Small Mammals ◽  
Human Case ◽  
Encephalitis Virus ◽  
Wild Mammals ◽  
Surveillance Studies ◽  
Predominant Species ◽  
Tick Borne Encephalitis ◽  
In The Wild ◽  
Tick Borne Encephalitis Virus

Although no human case of tick-borne encephalitis (TBE) has been documented in South Korea to date,5 surveillance studies have been conducted to evaluate the prevalence of tick-borne encephalitis virus (TBEV) in wild ticks.1-5 Four studies collected ticks by dragging or flagging in grassland and forest, while 1 study tested wild mammals (boars and rodents) by removing ticks from them. In the wild of South Korea, Haemaphysalis spp. were the predominant species found by tick dragging, while Ixodes nipponensis became predominant when harvested from small mammals.6

Small Mammals in Sweden as Hosts of Tick-Borne Encephalitis Virus and Vagrant Ectoparasites

Oikos ◽  
1967 ◽  
Vol 18 (1) ◽  
pp. 124 ◽  
Author(s):  
P. Brinck ◽  
A. Johnels ◽  
B. Lundholm ◽  
A. Svedmyr ◽  
G. von Zeipel ◽  
...  
Keyword(s):  
Small Mammals ◽  
Encephalitis Virus ◽  
Tick Borne Encephalitis ◽  
Tick Borne Encephalitis Virus

scholarly journals The Three Subtypes of Tick-Borne Encephalitis Virus Induce Encephalitis in a Natural Host, the Bank Vole (Myodes glareolus)

PLoS ONE ◽  
2013 ◽  
Vol 8 (12) ◽  
pp. e81214 ◽  
Author(s):  
Elina Tonteri ◽  
Anja Kipar ◽  
Liina Voutilainen ◽  
Sirkka Vene ◽  
Antti Vaheri ◽  
...  
Keyword(s):  
Bank Vole ◽  
Natural Host ◽  
Encephalitis Virus ◽  
Myodes Glareolus ◽  
Tick Borne Encephalitis ◽  
Tick Borne Encephalitis Virus ◽  
Bank Vole Myodes Glareolus

scholarly journals Tick-borne encephalitis virus isolates from natural foci of the Irkutsk region: clarification of the genotype landscape

2016 ◽  
Vol 61 (5) ◽  
pp. 229-234 ◽  
Author(s):  
O. V. Mel’Nikova ◽  
R. V. Adel’Shin ◽  
V. M. Korzun ◽  
Yu. N. Trushina ◽  
E. I. Andaev
Keyword(s):  
Small Mammals ◽  
Encephalitis Virus ◽  
Ixodes Persulcatus ◽  
Tick Borne Encephalitis ◽  
Irkutsk Region ◽  
High Virulence ◽  
Natural Foci ◽  
Tick Borne Encephalitis Virus ◽  
Relationship Of ◽  
Far Eastern

The Irkutsk region is the unique territory where all known subtypes of tick-borne encephalitis virus (TBEV) circulate. In the last years, the phenomenon of changes in TBEV subtypes (substitution of the Far-Eastern subtype by the Siberian one) was noted in some regions of the Russian Federation. The results of individual investigation of 11522 Ixodes persulcatus ticks and brain specimens from 81 small mammals collected in natural foci of the Irkutsk region during 2006-2014 are presented in the article. More than 60 TBEV strains have been isolated and studied by virological methods; E gene fragments (1193 b.p.) of 68 isolates have been typed. The majority of the strains (irrespective of subtype) were of high virulence for laboratory mice (LM) in case of both intracerebral and subcutaneous inoculation of virus. All isolates from warm-blooded small mammals and humans were of high virulence for LM, but placed in the same clusters of the phylogenetic tree with ticks collected in the same area. Tick-borne strains of different virulence also did not form separate clusters on the tree. Phylogenetic analysis showed that modern TBEV genotypic landscape of the studied territory is changing toward absolute predominance of the Siberian subtype (94.1%). This subtype is represented by two groups with prototype strains “Zausaev” and “Vasilchenko”. The “Vasilchenko” group of strains is spread on the whole territory under study; the strains of “Zausaev” group were isolated previously in the Irkutsk suburbs. The European subtype of TBEV circulates in natural foci of Pribaikalie permanently (at least 5% of the random sampling); the strains are of high virulence for LM. The Far-Eastern TBEV subtype was not found within the group of isolates collected in 20062014. The phylogenetic relationship of the strains under study had a higher correlation with the place of isolation than with the year or source.

Long-term presence of tick-borne encephalitis virus in experimentally infected bank voles (Myodes glareolus)

2021 ◽  
Vol 12 (4) ◽  
pp. 101693
Author(s):  
Anna Michelitsch ◽  
Christine Fast ◽  
Franziska Sick ◽  
Birke Andrea Tews ◽  
Karin Stiasny ◽  
...  
Keyword(s):  
Encephalitis Virus ◽  
Myodes Glareolus ◽  
Bank Voles ◽  
Tick Borne Encephalitis ◽  
Tick Borne Encephalitis Virus
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