One-Health surveillance of ticks and tick-borne diseases in Europe: Tick-borne Encephalitis (TBE) as a case study

• DOI: 10.1016/j.ijid.2024.107376
• Publication Date: 2025-02-28T19:40:30Z
• Authors: Dr Annapaola Rizzoli; Francesca Dagosti; Valentina Tagliap...; Giovanni Marini; Maria Bellenghi; Claudia Cataldo; Dr William Wint; Luca Busani
• Keywords: Infectious and parasitic diseases; RC109-216

Background/introduction: Tick-borne encephalitis (TBE) is a severe zoonotic neurological infection caused by the TBE virus (member of the Flaviriridae family), and it is considered to be one of the most important tick-borne viral diseases in Europe and Asia. In mainland Europe the main tick species transmitting the TBE virus is Ixodes ricinus. The infection is mostly acquired after a tick bite, but food-borne infection is also possible. TBE is a notifiable disease in EU/EEA since 2012. Despite the availability of a vaccine, its incidence is increasing with the appearance of new foci of virus circulation in areas previously unaffected. TBE prevention and mitigation of spill-over events could be obtained with One Health surveillance, which integrates traditional disease-based surveillance with the monitoring of drivers of disease emergence and early warning signals. This presentation focuses on the principal ecological and climatic drivers shaping TBE emergence in Europe and the use of environmental indexes as proxies for TBE infection risk. Methods: We searched available literature on covariates linked with the circulation of TBEV in Europe and assessed the best predictors for TBE incidence by means of statistical regression, using data on human TBE infections collected by the European Surveillance System (TESSy) and made available by The European Centre for Disease Prevention and Control (ECDC), averaged between 2017 and 2021. We then explored the relationship between the presence of human TBE cases across Europe and the habitat richness index (HRI) by means of binomial regression. Results: Among 31 different covariates, we selected eight variables from the best model, including factors linked to vegetation cover (i.e, Enhanced Vegetation Index and percentage of forested areas), climate (i.e, mean winter temperature, autumnal cooling rate and diurnal temperature range), and the probability of the presence of tick hosts, such as rodents and cervids. We also found a significant parabolic effect of HRI on the probability of the presence of human TBE cases in the European regions included in our dataset, with a TBE risk decline in areas with higher values of HRI. Discussion: In our studies, we summarized and statistically validated the covariates affecting the variability of TBE risk across Europe, which will serve as a basis for developing high-resolution risk models. Furthermore, we considered habitat richness as a proxy for disease risk, and our results suggest that in highly diverse habitats, TBE risk decreases. Conclusion: TBEV distribution is shaped by the interplay of multiple climatic, environmental, and ecological factors that exert a crucial role in the life cycle of ticks and TBEV circulation. We provided insights into the combination of covariates that appear to be crucial in affecting TBEV occurrence in Europe, defined their main data sources and established their interrelation with human TBE incidence at a continental scale. This study support competent authorities in deploying One Health integrated actions in existing and new potential risk areas.