Knowledge and awareness on vector-borne diseases: a pending subject for the Spanish society?

ABSTRACT Background: To evaluate the level of knowledge and risk perception regarding vector-borne diseases in the Spanish society and identify the risk factors associated with the level of understanding. Methodology: An online survey was conducted between January and May 2021, targeting Spanish adults. The survey consisted of 11 questions assessing knowledge and risk perception related to vector-borne diseases. Sociodemographic variables predicting the outcome variable (objective level of knowledge, determined by correctly naming two vector-borne diseases) were analyzed using multiple logistic regression. The outcome variable was then compared with the self-reported knowledge declared by the participants (kappa coefficient, k). Results: Out of the 1,646 respondents who completed the survey, 72.2% were female and 59.8% were >40 years old). Additionally, 87.3% showed a high risk perception and 61.7% understood what is a vector; however, only 36.3% had an objective level of knowledge (k= 0.353). The variables being >40 years (p <0.0001), having a monthly income >1,500 € (p <0.0001), and owning pets (p= 0.0423) were positively related with an objective level of knowledge on vector-borne diseases (adjusted effects). Conclusions: Both knowledge and perception of the risk on vector-borne diseases need to be strengthened in Spain, especially in regions where vector-borne diseases are endemic, emerging, or re-emerging. These preliminary results underscore the necessity of enhancing institutional efforts to build a robust knowledge base within the Spanish society, extending beyond scientific forums.


INTRODUCTION
Currently, vector-borne pathogens account for over 25% of all infectious diseases, causing millions of human deaths annually.Additionally, they have a significant impact on animal health and the global economy 1,2 .Although tropical and subtropical regions traditionally support the highest burden of vector-borne diseases (VBDs) 3 , a multifactorial set of factors now influences the global distribution of vectors and, consequently, the pathogens they transmit.Among these factors, climatic change stands out as the primary abiotic factor driving the widespread distribution of VBDs, as it significantly affects the biological cycle of vectors 4 .However, other human-related factors, such as population growth, globalization, changes in land use, and human migration, also contribute to the large-scale spread of VBDs 4,5 .This complex network of variables influencing exposure risk to vector-borne pathogens highlights the need for a broad, integrated approach to studying these diseases.
European countries bordering the Mediterranean Sea are significant hotspots for emerging and re-emerging VBDs 6 .The Mediterranean basin is particularly vulnerable to changes in VBD epidemiology due to potential variations in climatic conditions in the region 7 .For example, there has been an increase in VBDs in Spain, notably the West Nile and Crimean-Congo hemorrhagic fever viruses, among others 8,9 .Not only have these pathogens caused infections in animals, but also led to human deaths in the region 10,11 .
The significance of Spain as a hotspot for VBDs is enhanced by its strategic geographical location, which provides both a favorable climate for vector breeding and key stopover sites for migratory birds 12 .Despite the epidemiological evidence indicating that Spain is a hotspot for VBD affecting animals and humans, a recent study revealed a significant lack of knowledge and awareness about Chagas disease among the Spanish population 13 .
Although social factors directly affect the epidemiology of VBDs, more in-depth studies are needed to assess knowledge and risk perception.This information is key for developing effective prevention and control programs for at-risk populations.
This study aimed to evaluate the level of knowledge and risk perception among the Spanish population on VBDs and identify risk factors that influence the level of knowledge and awareness about these issues.

MATERIAL AND METHODS
A survey was conducted from January to May 2021 using an online questionnaire randomly distributed by a network of collaborators across all Spanish bioregions.The target population consisted of Spanish volunteers aged 18 and older; non-Spanish respondents were excluded.The questionnaire link was shared via social media, instant messaging apps, and e-mail distribution lists.All respondents were firstly informed about the study´s purpose and asked for their explicit consent to participate voluntarily.
The questionnaire was designed to assess knowledge and risk perception regarding VBDs and their risk factors.It included questions on general knowledge about vectors, VBDs, and clinical cases in humans and/or animals, as well as opinions on the impact of VBDs on humans, domestic animals and wildlife, and the awareness of politicians, scientists, and the public.The questionnaire also requested the following information: -Nationality -Age (years), categorized as 18-20, 21-30, 31-40, 41-50, 51-65, or >65 years old -Sex: Male / Female -Province of residence, framed within the Spanish bioregions (B1-B6) 14 -Population size of the area were the respondent lives: ≤50,000 / >50,000 inhabitants -University studies: Yes / No -Monthly income (in Euro, €), asked as <600 / 601-1,500 / 1,501-2,500 / 2,501-3,500 / 3,501-4,500 / >4 ,500; and re-categorized as ≤1,500 / 1,501-2,500 / >2,500 -Workplace: Indoor (inside a building) / Outdoors / Mixed / Other -Owner of domestic animals: Yes / No For all questions, the frequency and percentage (%) of responses in each category was calculated.The association between the response variable KN-VBD (Yes / No) and explanatory categorical variables (individual information) was initially assessed using Pearson's Chi-squared test or Fisher's exact test, as appropriate.Variables with p-values <0.10 were selected for inclusion in the multivariate analysis.Collinearity between variables was first assessed using the Cramer's V coefficient, selecting the variable with the highest biological plausibility; if a correlation coefficient >0.6 and a p-value <0.02 were obtained, the variable with the highest plausibility was selected.Finally, the influence of the selected explanatory variables on objective knowledge about VBDs (KN-VBD) was evaluated using logistic regression models, assuming a bino-mial data distribution and treating "province" as a random effect.The Akaike Information Criterion was used to select the most accurate model, resulting in the inclusion of age, monthly income, and ownership of domestic animals in the final model.Additionally, to assess reliability between self-reported knowledge on VBDs and actual knowledge (KN-VBD), a Kappa coefficient (k) was calculated and interpreted as slight (0.00-0.20), fair (0.21-0.40), moderate (0.41-0.60), substantial (0.61-0.80), and almost perfect (>0.80) 15 .Statistical significance was set at p <0.05, and all statistical analyses were conducted using the R software 16 .
Furthermore, to identify relationships among the most frequently reported VBDs by respondents, we used VOSviewer ® (http://www.vosviewer.com/) to identify clusters of terms extracted from their answers.VOSviewer ® is a free software for creating and visualizing semantic networks or term maps from scientific literature 17,18 .The software employs text mining and clustering functions to analyze the co-occurrence of terms and construct the semantic network 17 that is divided into thematic clusters, each represented by a different color.The diameter of the colored circles in the network corresponds to the frequency with which each term was cited in the reviewed publications.

RESULTS
A total of 1,646 responses were obtained from Spanish participants across all bioregions.The number of respondents ranged from 18 participants in B6 to 840 participants in B5 (Fig. 1).The response rate was higher among female participants (72.2%) and varied by age, ranging from 3.7% for responders aged 18-20 years to 29.4% for those aged 51-65 years.A larger number of responses was obtained from individuals aged >40 years (n=985; 59.8%).Additionally, 63.9% of the participants owned domestic animals and 85.7% had completed university studies (Table 1).Overall, 597 respondents (36.3%) demonstrated their knowledge by correctly naming at least two VBDs and were classified as KN-VBD.Among all participants, 87.3% expressed concern about VBDs, with 38.8% of them classified as KN-VBD.Similar patterns were observed among respon dents who claimed to know what a vector is (61.7%) and the diseases they transmit (94.3%); however, a lower percentage of these respondents were classified as KN-VBD (49.4% and 37.9%, respectively).These discrepancies between the participants´ self-reported knowledge and their actual understanding of VBDs (KN-VBD) were confirmed by a low kappa coefficient (k = 0.353), indicating a fair level of agreement.
Twenty-eight per cent respondents reported knowing a family member or friend affected by a VBD and 44.9% reported knowing of domestic animals with VBDs; 35.6% and 39.4% of these respondents were classified as KN-VBD, respectively.Approximately 80-90% of the participants believed that VBDs have negative health implications for domestic animals, wildlife, and humans, with 35-40% of them classified as KN-VBD.Regarding public opinion, the Spanish society perceived that scientists (66.1%) are the most concerned group about VBDs, followed by the general public (21.3%);only 3.6% of respondents considered VBDs a major issue for politicians (Table 2).Similarly, 33.1-42.2% of respondents who expressed concern about scientists, politicians, and general public were classified as KN-VBD.Additionally, participants who chose "I don't know", tended to have lower percentages of KN-VBD compared to those who answered "yes" or "no".Based on the univariate analysis, three out of eight explanatory variables were statistically associated with the level of knowledge about VBDs (KN-VBD).Specifically, the analysis revealed differences in KN-VBD across age groups, with respondents aged 21-30 years showing the highest level of knowledge (47.4%) and those >65 years the lowest (21.0%).Additionally, the proportion of KN-VBD was positively associated with monthly income and was higher among respondents with domestic animals (38.3%).In contrast, there were no statistical differences between knowledge about VBDs and Spanish bioregions (Table 3).The multivariate logistic regression model confirmed that age (<40 years), ownership of domestic animals, and a monthly income >1,500 € were the main factors associated with KN-VBD (Table 4).
The semantic network analysis conducted using VOSviewer ® revealed three predominant clus-ters.Among these clusters, malaria, Leishmania, yellow fever, and dengue were the most frequently mentioned pathogens and diseases.The most common word pairs included malaria-Leishmania, followed by malaria-dengue, malaria-yellow fever, and malaria-Chagas (Fig. 2).

DISCUSSION
Knowledge about VBDs among the Spanish population is lower than expected, as KN-VBD weakly correlates with respondents who selfreported understanding what a vector is and whether vectors transmit diseases.Regarding spatial distribution, our results suggest a homogeneous level of VBD knowledge across Spain.This is in line with the application of similar educational standards throughout the country and the national relevance of analogous endemic VBDs, as seen with Leishmania infantum 19,20 .
Although a small percentage of respondents know of family/friends or domestic animals affected by VBDs, the majority (>80%) are aware that these pathogens can have severe implications for domestic animals, wildlife, and humans.These differences reinforce our findings, indicating that many respondents are concerned about VBDs despite having no direct experience with them.This is consistent with the analyzed semantic network, where, of the most frequently mentioned pathogens by respondents, only two -Leishmania and the West Nile virus -are considered endemic and have significant health implications in Spain 11,19 .Our results suggest that the perception of VBDs among the Spanish society is primarily shaped by external information rather than personal experiences.This highlights the importance of investing in knowledge dissemination in non-scientific areas to maximize its outreach to society.
Overall, responders believe there is significant differences between VBD risk perception by scientists and those held by the general public.This suggests that the Spanish population recognizes the important role researchers play in the study of VBDs.The lowest awareness on VBDs among the studied groups is observed among politicians; only 3.6% of respondents believe they are concerned about VBDs.If this perception is confirmed, the difficulty in establishing preventive and control measures could have negative health implications.This is particularly concerning in the current epidemiological context of VBDs where competent authorities should remain vigilant.
The study reveals that younger respondents (<40 years old) possess a greater level of knowledge about VBDs.This is in line with the results by Sahoo et al. 21who reported that younger individuals generally have a higher level of knowledge of VBD compared to older adults.A previous study indicated that younger individuals are more likely to take protective measures against VBDs compared to older people 22 .Study participants who own pets possess greater knowledge about VDBs, which may be linked to the health impact of these diseases in domestic animals, as seen with leishmaniasis or the West Nile virus in dogs and horses, respectively 20,23 .In contrast, this information contradicts previous scientific data that indicate a general lack of knowledge among pet owners about diseases affecting their animals 24,25 .Additionally, a higher monthly income (>1,500 €) associates with greater knowledge about VBDs.Previous surveys suggest that lower incomes are linked to a weaker perception of disease risk 26,27 .
There are some limitations to this study.For instance, the underrepresentation of populations without internet access and the inability to verify the accuracy of the responses may have influenced the results.Regarding the employed methodology, volunteer participation may introduce bias, as respondents who chose to participate may have a higher awareness and knowledge about VBDs compared to those that had access to the questionnaire but chose not complete it 28 .Therefore, these methodological biases should be taken into account when interpreting the results.
The knowledge and risk perception of VBDs among the Spanish population are key issues that need to be strengthened in regions where VBDs are endemic, emerging, or re-emerging.Our results provide a foundation for further research and/or management strategies focused on VBDs, especially those with zoonotic implications.Additionally, educating the general public about VBDs from multiple perspectives, such as detection, prevention, and control, is crucial for building a solid knowledge base.To achieve this, institutional mechanisms should be enhanced, particularly through the dissemination of information about VBDs in non-scientific forums.This includes awareness campaigns on social media and TV, scientific outreach activities, and basic training in schools.

Figure 1 .
Figure 1.Distribution of respondents' answers across the six bioregions of Spain.

Figure 2 .
Figure 2. Relationships between pathogens and diseases caused by vector-borne diseases based on respondent terms identified by the semantic network.The network is divided into thematic clusters; blue cluster: Chagas, malaria, and West Nile; green: yellow fever, dengue, and zika; red: leishmania and filaria; Lyme disease is simultaneously linked to all three clusters.The diameter of the colored circles in the network corresponds to the frequency with which each term was cited in the reviewed publications.

Table 1 .
Characteristics of the respondents

Table 2 .
Frequency of responses of vector-borne disease risk and objective knowledge (KN-VBD) in the Spanish population VBD: vector-borne diseases.

Table 3 .
Variables associated with objective knowledge about vector-borne diseases (KN-VBD) among the Spanish population (univariate analyses)

Table 4 .
Variables associated to the objective knowledge about vector-borne diseases (KN-VBD) among the Spanish population (multivariate logistic regression model) OR: odds ratio; 95% CI: 95% confidence interval.