Tick-borne encephalitis case study

Tick-borne encephalitis (TBE) as a model for endemic pathogens transmitted by endemic vectors

Disease description

Tick-borne encephalitis (TBE) is a zoonotic disease which affects human and animal central nervous systems. Patients may experience flu-like symptoms in mild cases, while more severe cases can result in life-threatening complications. The virus is transmitted to humans through the bite of infected ticks or the consumption of unpasteurised milk and dairy products from infected animals. TBE has become a growing public health challenge in Europe and Asia. During the last decade, European incidence of TBE human cases increased from 2412 confirmed cases in 2012 to 3514 confirmed cases in 2022, with the appearance of new hotspots in non-endemic countries, and TBE has been identified as one of the biggest health threats arising from environmental change.

To enhance national and international preparedness and response to current and future spread of tick-borne encephalitis, MOOD has dedicated one case study to TBE.

Literature Review

Fig 1: Schematic representation of the study workflow

Fig 2: Most relevant drivers for TBE incidence selected through literature review and statistical analysis.

It is difficult to identify TBE risk areas, as the circulation of the TBE virus depends on the interplay between numerous environmental and ecological conditions. Hence, a literature review was performed to summarize all the different aspects that enhance TBE spread and identify the main forces that affect the distribution of TBE human infections in Europe.

Disease profile

To reach a comprehensive understanding of the factors affecting the ecology, distribution, and trend in Europe of the infectious diseases included in MOOD, information from the available literature and expert input was collected and summarized in “disease profiles”. These documents synthesize the available knowledge on specific diseases, such as TBE (In Press).

TBE Covariates Dashboard

Fig 3: A snippet of the dashboard for the exploration of TBE covariates

This tool allows to explore metadata about environmental and ecological covariates adopted in literature, with respect to tick-borne encephalitis. The dashboard is based on the results of a literature review performed on articles published between 2000 and 2021, focusing on European countries.

Publications

Ecological and environmental factors affecting the risk of tick-borne encephalitis in Europe, 2017 to 2021 (Dagostin et al., 2023, DOI 10.2807/1560-7917.ES.2023.28.42.2300121)

Correlation between airborne pollen data and the risk of tick-borne encephalitis in northern Italy (Marini et al., 2023, DOI 10.1038/s41598-023-35478-w)

High habitat richness reduces the risk of tick-borne encephalitis in Europe: A multi-scale study (Dagostin et al., 2024, DOI 10.1016/j.onehlt.2023.100669)

Mapping and predicting annual changes in tick-borne encephalitis risk in Europe – Submitted

Risk maps

Fig 4: Schematic representation of the modelling framework

Fig 5: TBE risk maps at the regional administrative level

Based on the information collected from literature, and a set of covariates that reflect both hazard and exposure dimensions, a spatio-temporal model was developed to predict the probability of human TBE occurrence across Europe at the regional and municipal administrative levels. The risk maps developed in this study will be regularly updated and used to predict the expected changes in TBE risk one year in advance, allowing prevention and response efforts to be focused on high-risk areas. These results will be helpful to inform targeted public health interventions, including vaccination programmes and awareness campaigns in areas where TBE is emerging.

Case study leaders

Fondazione Edmund Mach, Research and Innovation Centre, Francesca Dagostin (francesca.dagostin@fmach.it)

Finnish Institute of Health and Welfare, Timothée Dub

Fondazione Mach, Research and Innovation Centre, Annapaola Rizzoli (annapaola.rizzoli@fmach.it)

For more video content about TBE

Ecological and environmental factors affecting the risk of tick-borne encephalitis in Europe

During the MOOD Science Webinars, Francesca presented her work conducted within the MOOD project framework, focused on the assessment of the ecological factors that are shaping the spread of tick-borne encephalitis (TBE) in Europe, using official epidemiological data provided by the European Surveillance System (TESSy).

High habitat richness limits the risk of tick-borne encephalitis in Europe: a multi-scale study

So far, the relationship between biodiversity and TBE risk has been scarcely evaluated. Therefore by considering habitat richness as a proxy for biodiversity, Giulia Ferrari and her team modelled the association between the habitat richness index (HRI) and the distribution of human TBE cases across Europe. They validated their findings at local scale using municipality data collected in Trento and Belluno provinces, in northern Italy.

An exploratory study of the conditions for local actor engagement in tick and tick-borne disease risk management

Tick and Tick-borne disease (TBD) risk is dependent on interactions within complex, systemic networks of highly localized social and ecological variables. In the absence of effective programs, risk detection and prevention has become the responsibility of individuals at local scales, making them local actors in identifying and implementing solutions. In this PhD work, Iyonna and her team aimed to gain a holistic understanding of TBD risk from an actor-centered approach within its social-ecological dimensions.

Spatio-temporal spread of TBE in EU from 2012-2020

During the MOOD Science Webinar, Jasper presented his work on tick-borne encephalitis surveillance within the EU/EEA. This work was executed as part of his traineeship at ECDC. He provided a summary of changes in the epidemiology of tick-borne encephalitis between 2012 and 2020., and elaborated on some of the challenges related to data interpretation. The results can be used to update prevention strategies, including vaccination and health promotion campaigns, within the EU/EEA.

Game Animal Density, Climate, and Tick-Borne Encephalitis in Finland, 2007–2017

Tick-borne encephalitis (TBE) has become a growing public health challenge in Europe and other parts of the world. The number of human cases of TBE in all endemic regions of Europe has increased by almost 400% in the last 30 years; with spreading risk areas and new foci across Europe and worldwide, TBE has been included as one of the biggest health threats arising from environmental change. Novel assessment and monitoring strategies are therefore needed to face current and future outbreaks. For our first MOOD science webinar of 2022, we invited Timothee Dub, Research Manager in the department of Health security of the Finnish Institute for Health and Welfare (THL) to discuss the results of his paper published in Emerging Infectious Disease ‘Game Animal Density, Climate, and Tick-Borne Encephalitis in Finland, 2007–2017’.