Tick-Borne Encephalitis Virus Vaccination among Tourists in a High-Prevalence Area (Italy, 2023): A Cross-Sectional Study

Abstract

Tick-borne encephalitis (TBE) represents a potential health threat for tourists in high-risk areas, including the Dolomite Mountains in northeastern Italy. The present questionnaire-based survey was, therefore, designed in order to assess knowledge, attitudes, and preventive practices (KAP) in a convenience sample of Italian tourists visiting the Dolomite Mountains, who were recruited through online discussion groups. A total of 942 participants (39.2% males, with 60.2% aged under 50) filled in the anonymous survey from 28 March 2023 to 20 June 2023. Overall, 24.1% of participants were vaccinated against TBE; 13.8% claimed to have previously had tick bites, but no cases of TBE were reported. The general understanding of TBE was relatively low; while 79.9% of participants acknowledged TBE as a potentially severe disease, its occurrence was acknowledged as high/rather high or very high in the Dolomites area by only 51.6% of respondents. Factors associated with the TBE vaccine were assessed by the calculation of adjusted odds ratios (aOR) and 95% confidence intervals through a logistic regression analysis model. Living in areas considered at high risk for TBE (aOR 3.010, 95%CI 2.062-4.394), better knowledge on tick-borne disorders (aOR 1.515, 95%CI 1.071-2.142), high risk perception regarding tick-borne infections (aOR 2.566, 95%CI 1.806-3.646), a favorable attitude toward vaccinations (aOR 3.824, 95%CI 1.774-8.224), and a tick bite(s) in a previous season (aOR 5.479, 95%CI 3.582-8.382) were characterized as being positively associated with TBE vaccination uptake. Conversely, being <50 years old (aOR 0.646, 95%CI, 0.458-0.913) and with a higher risk perception regarding the TBE vaccine (aOR 0.541, 95%CI 0.379-0.772) were identified as the main barriers to vaccination. In summary, tourists to the high-risk area of the Dolomites largely underestimate the potential occurrence of TBE. Even though the uptake of the TBE vaccine in this research was in line with European data, public health communication on TBE is required in order to improve acceptance of this effective preventive option.

Keywords: attitudes; encephalitis; health knowledge; practices; tick-borne diseases; tick-borne encephalitis virus; travel medicine; vaccines.

Figure A1

Triveneto Region and the Dolomite mountain ranges (https://commons.wikimedia.org/wiki/File:Alps_location_map.png (access on 1 August 2023); https://it.wikipedia.org/wiki/Regione_ecclesiastica_Triveneto#/media/File:Ecclesiastical%20region%20Triveneto%20in%20Italy.svg (access on 1 August 2023)). The Dolomites are a well-confined mountain range in northeastern Italy in the eastern part of the Southern Alps, between the Austrian border in the north and the Venetian plain in the south (Appendix A, Figure A1) [41,82,83]. With an average height under 3000 m and their highest peak (the Marmolada Mountain) at an elevation of around 3343 m above sea level, the Dolomites are relatively low compared to nearby ranges. Their area (15,942 km²) is shared by the Italian provinces of Belluno, Vicenza, Verona, Trento, Bolzano, Udine, and Pordenone. The alpine climate of the Dolomites is characterized by harsh winter temperatures and summer heavy rainfall [82,83], but compared to the border regions of Austria and Switzerland, the Dolomite Mountains are characterized by warmer temperatures and less precipitation; therefore, they are highly accessible in both the cold and warm seasons. These features, as well as being one of the 218 natural UNESCO world heritage sites, collectively contribute to their wide tourism appeal, with far more than 20 million overnight stays per year [41]. To date, Ixodes ticks are usually found at altitudes < 1500 m above sea level from spring to autumn at temperatures above 10 °C, even though global warming is progressively raising this altitude level [31,84,85].

Figure A2

Distribution of the general knowledge score (GKS; a), a summary score for symptoms associated with tick-borne diseases (symptoms score; b), a risk perception score (RPS) for tick-borne diseases (c), and the RPS for side effects of the TBE vaccine (d). For all sum scores, distribution did not pass a normality check according to the D’Agostino–Pearson test (GKS: K2 = 63.71, p < 0.001; symptom score: K2 = 37.55, p < 0.001; RPS for natural infection: K2 = 30.11, p < 0.001; RPS for the TBE vaccine: K2 = 569.1, p < 0.001).

Figure A2

Distribution of the general knowledge score (GKS; a), a summary score for symptoms associated with tick-borne diseases (symptoms score; b), a risk perception score (RPS) for tick-borne diseases (c), and the RPS for side effects of the TBE vaccine (d). For all sum scores, distribution did not pass a normality check according to the D’Agostino–Pearson test (GKS: K2 = 63.71, p < 0.001; symptom score: K2 = 37.55, p < 0.001; RPS for natural infection: K2 = 30.11, p < 0.001; RPS for the TBE vaccine: K2 = 569.1, p < 0.001).

Figure A3

Frequency of acute (a) and chronic (b) symptoms associated with tick-borne infections, as reported by the 942 Italian subjects participating in the survey. In both cases, the number of respondents either agreeing or strongly agreeing with the presented sign/symptom is reported.

Figure A3

Frequency of acute (a) and chronic (b) symptoms associated with tick-borne infections, as reported by the 942 Italian subjects participating in the survey. In both cases, the number of respondents either agreeing or strongly agreeing with the presented sign/symptom is reported.

Figure A4

Occurrence of tick bites, as reported by 942 participants (Italy, 2023), shown according to age group.

Figure A5

Number of preventive measures reported by 156 participants with a previous history of tick bite(s). Overall, the share of respondents reporting no preventive measures was 55.56% in the 30–39 age group, 43.75% in the 40–49 age group, 27.27% in the 50–59 age group, 10.00% in the 60–69 age group, and 20.00% in ≥70-year-old respondents, while participants aged 20–29 years all reported 2 preventative measures.

Figure 1

Flow chart for the participants included in the final sample.

Figure 2

Summary of the perceived probability of contracting a TBEV infection (E^inf); perceived probability of developing complications after the delivery of the TBE vaccine (E^vac); perceived severity of natural infection from TBEV (C^inf); perceived severity of the vaccine side effects (C^vac), as reported by 942 participants (Italy, 2023).

Figure 3

Vaccination rates for TBE according to age group, as reported by 942 participants (Italy, 2023).

Figure 4

Reasons for receiving (a) and not receiving (b) the TBEV vaccination protocol, as reported by 942 participants (Italy, 2023).