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Prevalence of Tick-borne encephalitis virus in Ixodes ricinus and Dermacentor reticulatus ticks in Lithuania
Date Issued |
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2019 |
Tick-borne encephalitis (TBE) is a typical zoonosis disease mainly transmitted to humans by hard ticks Ixodidae family, mainly Ixodes ricinus and Ixodes persulcatus. It is known that also Dermacentor reticulatus is involved in circulation of TBE virus (TBEV). Tens of thousands of people are hospitalized in the world every year, so it has become an international public health problem. One Abstracts 2019 • Weimar, Germany 125 third of European TBE cases are detected in the Baltic States. Lithuania is one of the countries with the highest number of reported TBE cases in Europe: an average of 450 cases of TBE are reported every year. Distribution of TBE cases in Lithuania varies between different regions and the highest annual incidences of disease are registered in northern and central part of the country. The aim of this study was to investigate the current prevalence of TBEV in ticks and genetically characterize the strains of virus distributed in Lithuania. From March-September 2017 and April-October 2018 ticks were collected from different Lithuanian counties and analyzed for the presence of TBEV. A total 5033 ticks (4001 I. ricinus and 1032 D. reticulatus) were collected and grouped in 544 pools. For the detection of TBEV a quantitative real-time Revers transcription-PCR (RT-PCR) was performed. Samples positives by real-time PCR were used for one step RT-PCR and for nested PCR for future sequencing of the partial E protein and NS3 genes. Twenty-three (4.2%) pools were found positive for TBEV, with an overall estimated minimum infection rate (MIR) of 0.45%. TBEV was detected in both tick species with MIR 0.58% in D. reticulatus and 0.42% in I. ricinus. TBEV-infected ticks were found in five counties (Vilnius, Kaunas, Marijampolė, Alytus, Šiauliai) with MIR ranged from 0.11% to 1.84%. The phylogenetic analysis has shown that detected strains belong to the European subtype but have some specific genetic variants.
art. no. TBEV-11