TICK-BORNE ENCEPHALITIS VIRUS PREVALENCE IN EUROPEAN TICK POPULATIONS: A GEOGRAPHIC PERSPECTIVE

Abstract

Objectives. Tick-borne encephalitis virus (TBEV) poses a significant public health threat in Europe. This systematic review investigates TBEV prevalence and expansion across 26 countries to evaluate shifting transmission risks and the emergence of new microfoci. Material and Methods. Following PRISMA 2020 guidelines, PubMed and Scopus were searched for studies published between 2004 and 2024. To address methodological heterogeneity, data were categorized by individual prevalence, minimum infection rate (MIR), and estimated pooled prevalence (EPP). Results. From 86 manuscripts (selected from 354 records), data synthesis revealed significant northward (65.1°N in Norway) and vertical expansion into Alpine regions (1,109 m a.s.l.). While Ixodes ricinus remains the primary vector, Ixodes persulcatus in the Baltic zone exhibited substantially higher infection rates (MIR 3.0–4.6%). In emerging zones (the UK, Belgium, Romania), tick-derived MIR was frequently <1%, whereas animal seroprevalence (2.61–15.02%) proved a more sensitive indicator of viral circulation. Genomic outliers, such as the Far-Eastern subtype in Moldova, suggest non-linear dispersal mechanisms. Conclusion. TBEV distribution is highly dynamic, driven by climate-mediated range shifts and the silent establishment of new microfoci. Traditional tick screening often underestimates risk in emerging areas, necessitating a transition to integrated One Health surveillance. Combining entomological monitoring with veterinary seroprevalence is critical for accurate risk assessment and the implementation of targeted vaccination campaigns in the evolving European landscape. Keywords: tick-borne encephalitis virus, TBEV, prevalence, ticks, Europe