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Thursday 19th September

8:30 Registration
9:00 Opening remarks
9:15 - 10:00 First group activity
10:00 -10:20 Keynote Speech
Olivier Briet (European Center for Disease Prevention and Control)
Risk assessment of Aedes-borne diseases and the need for modelling tools for decision-making
With Aedes albopictus spreading in Europe and outbreaks of Aedes-borne diseases occurring with increasing frequency, there is an increasing need for tools to estimate the risk of these diseases and inform public health control strategies. This talk discusses statistical and mathematical modelling approaches for risk assessment and scenario modelling, including data needs on the cost-effectiveness of interventions.
10:20 -11:00 Training data session: Experimental data
Chair: Ruth Müller (Institute of Tropical Medicine, Belgium)
10:20 A review of temperature-dependent life-history traits of Aedes species
Paul Huxley (Virginia Polytechnic Institute and State University, USA; Imperial College London, UK)
Many disease vectors are small ectothermic organisms, so many of the biological traits that determine their distribution and abundance patterns, such as development and reproduction, are sensitive to variation in environmental temperatures. This temperature-dependence of vector and pathogen traits has been used to predict how climatic warming could affect future VBD risk. For example, by 2050, around 2.5 billion more people are predicted to be at—risk of contracting dengue as some geographical areas become more suitable for mosquitoes with warming. Recent surges in local dengue transmission across Europe have been partially attributed to how ongoing seasonal temperature changes have increased the region’s thermal suitability for the Aedes albopictus mosquito, an important dengue vector. However, most current projections of how warming will influence VBDs assume that all populations of a given vector species respond similarly to temperature. This assumption may not be appropriate because temperature variation is a selection pressure that can lead to local adaptation. If species are made-up of multiple locally adapted populations, assuming a single species—level response might lead to inaccurate predictions of future VBD risk, which, ultimately, could cost lives. To test this hypothesis, we conducted a global synthesis and analysis of the available temperature–trait data on Aedes mosquitoes. So far, this work seems to suggest that predictions that ignore local adaptation to temperature are indeed likely to overestimate or underestimate VBD risk. This finding has important implications for VBD risk modelling and control strategy implementation.
10:40 A review on the effect of precipitation and water availability on Aedes mosquitoes life history traits
Emmanuelle Kern (Imperial College London, UK)
Rainfall is crucial for mosquito reproduction and population dynamics, as it creates breeding sites in stagnant water. Therefore, rainfall plays a key role in modelling the risk of Aedes-borne diseases by linking climatic conditions to mosquito activity and disease transmission potential. A good understanding of the relationship between rainfall and mosquito survival and development is, therefore, essential to incorporate rainfall into models, particularly mechanistic models. This talk summarises the current published laboratory evidence on the relationship between rainfall and evaporation, and Aedes species' life history traits.
11:00-11:30 Coffee & Tea Break
11:30 - 12:30 Training data session: Surveillance data
Chair: Giovanni Marini (Edmund Mach Foundation, Italy)
11:30 VectAbundance: a spatio-temporal database of vector observations
Giovanni Marini (Edmund Mach Foundation, Italy)
VectAbundance is an open-access database that provides harmonised, high-quality egg count data of Aedes albopictus from 2010 to 2022 across Albania, France, Italy, and Switzerland. By offering standardised observations, VectAbundance supports public health agencies in improving the reliability of vector abundance models and enhancing preparedness efforts.
11:50 Vectornet: past, present and future
William Wint (University of Oxford, UK)
VectorNet is an EFSA/ECDC-funded project that has been running in various forms since 2008. It aims to collect mosquito, tick, sandfly and biting midge vector distribution data for Europe and its neighbours. the data originate from publications, fieldwork and a large network of contributors. Data validation is key. Polygon vector status maps are released every 3 to 6 months for about 40 priority species, which have become an “industry standard”. All data are available upon request. A new Project phase started in June 2024 which will make significant changes and additions to the data and its dissemination.
12:10 Leveraging VectorBase/VEuPathDB Mosquito Data for Enhanced Modeling
Robert Maccallum (Imperial College London, UK)
In this presentation, I will discuss the mosquito data available through VectorBase/VEuPathDB that is relevant to modeling efforts. The focus will be on counts of different mosquito species collected at regular intervals across various locations. Proper curation and storage of metadata—such as trap type, attractant used, number of traps, and duration of trap operation—are crucial. They enable modelers to filter data effectively and ensure consistency, even when integrating information from multiple data providers, which is one of our central goals. This also allows for the appropriate calculation of abundance measures. Technical concepts to be covered include the challenges associated with storing zero-count observations, which can increase data volume by up to 20 times. Additionally, I will describe the use of ontologies in standardizing fields across multiple data providers, facilitating better data integration and analysis. I will also address the current funding status and long-term sustainability of VectorBase/VEuPathDB, including interactions with sister projects and databases such as VecDyn, which continues to curate surveillance data.
12:30 - 13:30 Lunch
13:30 - 15:10 Mechanistic models session
Chair: Bethan Purse (Centre for Ecology and Hidrology, UK)
13:30 Environmentally driven delay-differential equation models for Aedes albopictus
Dominic Brass (Centre for Ecology and Hidrology, UK)
The incidence of vector-borne disease is on the rise globally, with burdens increasing in endemic countries and outbreaks occurring in new locations. Effective mitigation and intervention strategies require models that accurately predict both spatial and temporal changes in disease dynamics, but this remains challenging due to the complex and interactive relationships between environmental variation and the vector traits that govern the transmission of vector-borne diseases. Predictions of disease risk in the literature typically assume that vector traits vary instantaneously and independently of population density, and therefore do not capture the delayed response of these same traits to past biotic and abiotic environments. We argue here that to produce accurate predictions of disease risk it is necessary to account for environmentally driven and delayed instances of phenotypic plasticity. To show this, we develop a stage and phenotypically structured model for the invasive mosquito vector, Aedes albopictus, and dengue, the second most prevalent human vector-borne disease worldwide. We find that environmental variation drives a dynamic phenotypic structure in the mosquito population, which accurately predicts global patterns of mosquito trait-abundance dynamics. In turn, this interacts with disease transmission to capture historic dengue outbreaks. By comparing the model to a suite of simpler models, we reveal that it is the delayed phenotypic structure that is critical for accurate prediction. Consequently, the incorporation of vector trait relationships into transmission models is critical to the improvement of early warning systems that inform mitigation and control strategies.
13:50 VEClim - an early warning support system for climate-sensitive vector-borne diseases
Kamil Erguler (The Cyprus Institute, Cyprus)
The Climate-Driven Vector-Borne Disease Risk Assessment project (VEClim), supported by the Wellcome Trust as part of Digital Technology Development Awards in Climate-Sensitive Infectious Disease Modelling, aims to improve vector-borne disease prediction and management by employing data-driven, mechanistic, and climate-sensitive geographical modelling to represent vector populations and disease transmission. The VEClim platform features a user-friendly web-based GIS designed as a versatile interface to improve accessibility to the models and to present short-, medium-, and long-term predictions of habitat suitability, vector activity, and disease risk and impact. The platform displays vector presence and risk maps and seasonal profiles of vector activity and disease risk. It is planned to include (i) an extensive database of meteorological variables, climate projections, and environmental covariates and (ii) an up-to-date longitudinal vector surveillance dataset. Customised simulations under different climate scenarios and vector control activities will also be possible. A comprehensive application programming interface (API) will extend the capacity of advanced data analysis tools, such as Python and R, to accommodate climate-sensitive mechanistic modelling. The platform is operationally maintained at The Cyprus Institute and is permanently available via its dedicated domain: veclim.com.
14:10 ArbocartoR: an operational spatial modelling tool to predict the dynamics of Aedes mosquito species from weather and environmental variable
Pachka Hammami (Centre de coopération internationale en recherche agronomique pour le développement, France)
arbocartoR is a R package and companion web interface, designed to support vector control activities design. It allows generating simulations from a multi-level model including two different components: the deterministic population dynamics of Aedes mosquitoes (Ae. albopictus and Ae. aegypti) in various environments and the stochastic dynamics of transmission of dengue, Zika and chikungunya viruses. The underlying model is a spatialized compartmental model considering that mosquitoes and humans reside in independent parcels where their respective densities are assumed to be homogeneous. Humans can move between parcels, spatially spreading the diseases. Mosquito dynamics are mainly driven by rainfall, temperature, and land use (main covariates identified in the scientific literature). Using the tool, the user can modify the importation of viruses by humans, and characterize the implementation of various vector control strategies. A set of synthetic outputs of the simulations is provided including the daily dynamics of mosquito populations, and vector/host infections; a map displaying the spatialized and temporal dynamics of the R0 over the simulation period and area; and the prediction intervals of the number of autochthonous infections and disease spread.
14:30 Impact of climate and weather on Aedes albopictus in Italy
Miguel Garrido Zornoza (University of Copenhagen, Denmark; International Centre for Theoretical Physics, Italy)
Aedes albopictus is now well established in Italy since its introduction, with paramount public health implications. We adapted the VECTRI model, originally developed to simulate malaria transmission, to Ae. albopictus. The model was calibrated and validated using 12y ovitrap data for the Emilia Romagna region. VECTRI reproduces the vector seasonality and, to a lesser extent, its interannual variability. Adult density hotspots coincide with populated Italian cities, such as Rome, Milan, Naples, Foggia, Catania, Palermo, Lecce, Cagliari, Genoa, Turin and large urban centres in Emilia-Romagna. Low risk was simulated over the mountain regions. We show a lengthening of the mosquito season of about 1-3 weeks per decade, depending on the region. Summer heatwaves can have a detrimental effect on simulated adult density over the warmest southern part of Italy, while they can be beneficial over regions that are more temperate.
14:50 dynamAedes: a unified modelling framework for invasive Aedes mosquitoes
Daniele Da Re(University of Trento; Edmund Mach Foundation, Italy)
Mosquito species belonging to the genus Aedes have attracted the interest of public health officers both for their plastic biology and for their competence and efficient transmission of debilitating viruses. Unravelling the physiological and behavioural traits of such species is crucial for understanding and predicting their spatial and temporal population dynamics, thus helping to direct actions to mitigate invasive Aedes local densities. In the R package dynamAedes, we synthesised the life cycle of four invasive Aedes species (Ae. aegypti, Ae. albopictus, Ae. japonicus, and Ae. koreicus) in a single multi-scale, stage-based, and time-discrete probabilistic modelling framework, informed and driven by temperature observations and photoperiod length. Temperature-dependent and photoperiod-dependent life-cycle parameters – e.g. egg survival, percentage of diapausing eggs laid – were inferred through data extracted from the scientific literature. dynamAedes can be applied to three different spatial scales: punctual, local, and regional, accounting for both active and passive dispersal of the modelled mosquito species as well as for the heterogeneity of the available temperature datasets. dynamAedes is a flexible tool that could be used for applications related to the management of invasive Aedes populations as well as for more theoretical ecological inquiries. The open-source nature of this model allows for a quick update of the model parameter based on new scientific findings, as well as further implementation of different features such as inter and intra-specific competition and mosquito control actions.
15:10 - 15:30 Coffee & Tea Break
15:30 - 16:50 Correlative models session
Chair: Roberto Rosà (University of Trento, Italy)
15:30 Correlative and mechanistic modelling to advise surveillance and control actions of Aedes albopictus in the Netherlands
Adolfo Ibáñez-Justicia (Centre for Monitoring of Vectors, Netherlands Food and Consumer Product Safety, The Netherlands)
The Asian tiger mosquito (Aedes albopictus) was found for the first time in The Netherlands in 2005 inside Lucky bamboo greenhouses. Since then, many introductions have also occurred at outdoor locations implicating intensive surveillance and control actions to prevent the establishment of populations in the country. The Centre for Monitoring of Vectors, responsible for setting up surveillance and control actions, has developed three models for the tiger mosquito with different goals. A habitat suitability model using MaxEnt, occurrence data and bioclimatic variables was developed to understand the habitat suitability for the species in the country. The second model was a mechanistic model, based on published temperature thresholds for the species and gridded daily temperature data, which aimed to map the probability of overwintering of eggs, the probability of adult survival, and the probability of life-cycle completion to the adult stage. Results obtained with the correlative and mechanistic models can be contrasted with the findings of Ae. albopictus during surveillance to establish relationships considering the possibility of overwintering and survival of the species at these locations. Lastly, a growing degree days-based mechanistic model was created using gridded daily temperature and photoperiod length to estimate the first egg hatchings and larval development time throughout the Netherlands, and to adjust the timing of larvicidal treatments at the national level. The last model incorporates 15 days of temperature predictions to help plan the activities. A similar model will be developed to estimate the end of the adult trapping season, and the end of larvicidal treatments.
15:50 Inferring the seasonality of Aedes albopictus in the Emilia-Romagna region (Italy)
Alessandro Albieri (Centro Agricoltura Ambiente "Giorgio Nicoli", Italy)
Aedes albopictus, the Asian tiger mosquito, has become a prevalent pest in Italy, causing severe nuisance and posing a threat to the transmission of arboviruses introduced by infected travellers. We propose a predictive correlative model on the seasonal population density of Ae. albopictus in the Emilia-Romagna region based on ovitrap data and meteorological parameters. A Bayesian approach was employed to identify the best meteorological predictors of species trend and seasonality, using the eggs collected monthly from 2010 to 2022 by the Emilia-Romagna regional monitoring network for predicting mosquito season 2023 in the Emilia-Romagna region. The data collected confirmed the impact of climate parameters on the Ae. albopictus population’s seasonal trend.
16:10 Machine learning and stacked generalisation to forecast the spatio-temporal abundance of Aedes albopictus
Marharyta Blaha (University of Trento, Italy)
Modeling the temporal and spatial dynamics of species phenology relies on various techniques, with correlative models being commonly used to establish statistical relationships between response variables (e.g., species abundance) and abiotic predictors. The choice of modelling algorithm is critical, as different models applied to the same dataset can yield variable outcomes. To address this, ensemble techniques like stacked generalization have proven effective in producing robust predictions. Stacked models combine predictions from multiple base learners, which are then synthesized by a meta-learner to generate a final, reliable output. This study applied a stacked machine learning model to a 13-year dataset of Aedes albopictus egg abundance, gathered through ovitraps in the Emilia-Romagna region, Italy. Using environmental covariates and 2023 data for testing, we predicted weekly mosquito egg numbers. To evaluate model robustness, we developed 100 different models by iteratively subsampling the dataset, varying the number of locations and years used for training. The training data spanned four timeframes (2011-2022, 2015-2022, 2019-2022, and 2021-2022), with five sample fractions (0.10, 0.25, 0.50, 0.75, and 0.90) tested for each period. Each combination underwent five iterations to ensure consistency. This approach enabled us to: i) determine the data needed for reliable predictions; ii) generate spatio-temporal explicit forecasts for locations not covered by traditional monitoring; and iii) provide insights to regional authorities for mosquito control in 2024 using the best-performing model. This modelling framework, though applied to Aedes albopictus, offers a versatile tool for forecasting the abundance of various species, enhancing its utility for ecological and public health applications.
16:30 Modeling the spatiotemporal abundance of Aedes species and the risk of arboviral infection in Europe and the Americas
Agnese Zardini (Bruno Kessler Foundation, Italy)
Assessing the spatiotemporal distribution of different mosquito vector species and the associated risk of arbovirus transmission is crucial to designing effective policies of disease control and prevention strategies. We developed a computational model to quantify the daily abundance of Aedes mosquitoes and the consequent risk of autochthonous transmission of dengue virus, Zika virus, and chikungunya in Europe and the Americas at a high spatiotemporal resolution. The model is calibrated on data from mosquito adults collected in 115 locations on the two continents. The approach provides estimates of mosquito abundance in areas where no entomological surveillance is available, using only data on the local temperature and precipitation. We found that, in regions colonised by both Aedes species, Ae. aegypti represents the main vector for the transmission of dengue, Zika, and chikungunya viruses. These arboviruses were estimated to be endemic in many tropical and subtropical regions of the Americas. Our results highlighted non-negligible transmission risks also for the US and, in particular, for Florida, Texas, and Arizona. The broader ecological niche of A albopictus may contribute to causing chikungunya outbreaks and clusters of dengue autochthonous cases in temperate areas of the Americas and in Mediterranean Europe. Obtained results provide a comprehensive overview of the potential transmissibility of Aedes-borne arboviral infections in Europe and the Americas, identifying areas where prioritizing entomological and epidemiological surveillance activities and planning information campaigns and preventive measures.
19.30 Social dinner downtown
We meet at the restaurant "Va Mo La" (Via delle Moline 3/A, Bologna).
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Friday 20th September

9:00 - 10:30 Group activity
This session will begin with a summary of the previous day's group activity, followed by a concise presentation summarising the comparisons of the different models we have seen the day before. We will use this information to guide our discussion in groups.
10:30 - 11:00 Coffee & Tea Break
11:00 - 12:45 Group activity
Plenary discussion.
12:45 - 13:00 Concluding remarks