Investigation of Tick-borne encephalitis in Ixodes ricinus and dermacentor reticulatus

Abstract

During the last few decades the incidence of the Tick-borne encephalitis (TBE) disease has been increasing and becoming a growing health problem in almost all endemic European and Asian countries. TBE virus (TBEV) can be transmitted to people by a bite of Ixodes spp ticks, Ixodes persulcatus, Ixodes ricinus and Dermacentor reticulatus. Lithuania is one of the countries with the highest number of reported TBE cases, an average of 450 cases of TBE are reported every year. The aim of this study was to investigate the current prevalence of TBEV in different species of ticks and genetically characterize the strains of virus distributed in Lithuania. In March-September 2017, 1884 ticks (267 pools) were collected from eight Lithuanian counties, 18 regions. Gathered ticks were identified as I. ricinus (n=1351) and D. reticulatus (n=533). 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. In the collected ticks I.persulcatus ticks weren’t detected. The phylogenetic analysis of NS3 and E genes sequences has shown that detected strains belong to the European subtype and are specific for Lithuania.