The growing threat of vector-borne diseases, many of which are climate-sensitive, demands more robust monitoring systems and coordinated response efforts in both endemic and emerging regions. Climate change, expanding mosquito habitats and seasons, and shifting bird migration patterns drive the spread of diseases like West Nile virus (WNV) into new areas.

In response to these challenges, a team of international researchers affiliated with leading European initiatives, including the research projects  IDAlert and E4Warning and the Dutch Pandemic and Disaster Preparedness Center (PDPC), gathered at the Centre for Advanced Studies of Blanes (CEAB-CSIC) to discuss and enhance our understanding of the ecological pathways of WNV circulation and transmission within European wetlands. Their objective was to share and develop more integrated and effective surveillance strategies that bring together data on vectors, avian host dynamics, and their interactions, strengthening early warning capabilities and preparedness in the face of a changing climate and land use transformations.

Wetlands as crucial sentinels: integrated approaches

Wetlands and their peri-urban surroundings are recognized as critical hotspots for the surveillance of vector-borne diseases like WNV. These landscapes represent complex socio-ecological interfaces where natural and human-modified environments converge.

This ecologically rich region, characterized by wetlands and rice fields, provides ideal breeding grounds for mosquitoes and critical habitat for both resident and migratory birds, key components in the WNV transmission cycle. During the summer months, the human population in the area more than doubles due to seasonal tourism, significantly increasing the risk of human exposure to emerging pathogens.

As a result, Aiguamolls serves as a strategic study site for the E4Warning and IDAlert projects, offering an ideal setting to investigate the ecological drivers of arboviral circulation and to test innovative field tools. A central goal of this work is to improve the collection of blood-fed female mosquitoes, which can be analyzed to determine their host feeding preferences, providing insight into potential transmission routes of WNV.

To share and develop more integrated and effective surveillance strategies, a three-day meeting was organized. During this visit, one of the key goals was to further explore collaboration and comparison with wetlands near Rotterdam, another study site shared by the PDPC and IDAlert projects. By contrasting ecological dynamics and surveillance methods between these northern and southern European wetlands, researchers aim to better understand regional variability in West Nile virus circulation and improve transnational early warning systems.

Throughout the meeting, researchers carried out intensive fieldwork within the park, deploying BG-Sentinel and resting traps, and conducting mosquito aspirator sampling across a range of habitats, including rice fields, wetlands, and peri-urban areas. Furthermore, participants explored the use of passive acoustic monitoring systems to assess bird community composition and detect shifts that may impact viral dynamics. These acoustic tools offer new opportunities to track the presence and behavior of avian reservoir species over time.

Complementing these efforts, researchers received hands-on training in the use of FTA cards, which are small sampling devices placed in the field to collect mosquito saliva. These cards, developed at Erasmus MC, enable the non-invasive detection of arboviruses using molecular techniques and represent a promising method for monitoring viral circulation.

A meeting shaped by diverse expertise and career stages

One of the key strengths of the gathering was the rich diversity of disciplines and career stages represented, fostering dynamic exchange and cross-pollination of ideas. The meeting brought together experts in epidemiological modeling, virology, vector ecology, and environmental science, creating a vibrant forum for advancing integrated approaches to climate-sensitive disease surveillance.

Among the participants was Joacim Rocklöv, from Heidelberg University (Germany), coordinator of the IDAlertEuropean project, which focuses on understanding how climate change influences the emergence and transmission of infectious diseases to strengthen Europe’s public health resilience. He was joined by PhD candidate Julian Heidecke, who contributed to the modeling and risk assessment discussions.

Reina Sikkema, a virologist from Erasmus MC (The Netherlands), participates in IDAlert and represents the Pandemic and Disaster Preparedness Center (PDPC), which brings together experts to improve readiness for emerging health threats. She co-leads a frontrunner project at PDPC together with Maarten Schrama, ecologist, from Leiden University, who also participated. Within a large transdisciplinary team, they investigate how salinization and landscape change influence the ecology of mosquitoes and birds and how these changes modulate the risk of virus transmission. They were accompanied by team members Jordy Van der Beek, Tijmen Hartung, and Erley Lizarazo, each contributing to the interdisciplinary dialogue.

Local hosts from the Centre for Advanced Studies of Blanes (CEAB-CSIC) included Frederic Bartumeus, co-director of Mosquito Alert, coordinator of the E4Warning project, and partner in IDAlert. He was joined by his research team members Alex Richter-Boix, Catuxa Cerecedo-Iglesias, PhD candidates Nina Bogdanovic and Júlia Rodriguez-Grabalosa, and Olatz San Sebastián; Elisa Mora and Santi Escartín from the Mosquito Alert operational team.

Throughout the workshop, participants engaged in rich, collaborative discussions focused on the development of scalable, ecological, and epidemiological risk indicators, combining traditional and novel technologies in the field, e.g., smart mosquito traps (with automated count and identification of mosquito species), field-grounded molecular techniques, and automated acoustic recording of birds. Together, they explored strategies to model and forecast the risk of WNV and other climate-sensitive vector-borne diseases across Europe, leveraging the strengths of diverse data streams and scientific perspectives.

The E4Warning project participated in the GEO Global Forum 2025, held from May 5–9 at the Auditorium della Tecnica in Rome, joining over 60 Horizon Europe-funded projects in presenting cutting-edge Earth Observation (EO) solutions for sustainable development and global health security.

As part of the EU Booth, E4Warning presented its poster on EO-driven risk assessment for mosquito-borne diseases, highlighting how satellite data and environmental covariates are used to model the habitat suitability of key West Nile virus (WNV) vectors and avian reservoirs across Europe. Our contribution emphasized the importance of dynamic, seasonally resolved models to improve early warning systems for WNV and other vector-borne threats.

The event also marked the adoption of the GEO Post-2025 Strategy, reaffirming the role of EO in addressing climate adaptation, environmental resilience, and global health. Throughout the week, the EU Booth hosted a rich program of live talks, e-posters, expert meetups, and thematic sessions, making it a key hub for showcasing how EO can bridge science, policy, and impact.

The EuroGEO Secretariat published all presentations (PDF), as well as all e-posters, on their Web site: GEO Global Forum 2025 Marks Milestone in Earth Observation Collaboration. Especially the e-poster gallery EuroGEO – e-posters will be promoted on social media towards the next EuroGEO workshop that will be announced soon.

In November, Kamran Safi from the Max Planck Institute of Animal Behavior visited the CEAB-CSIC team leaded by Frederic Bartumeus and the Girona study area: the Aiguamolls de l’Empordà Natural Park. This visit was instrumental in familiarizing with the study area and engaging with local stakeholders: the park staff, regional mosquito control officials, and local ornithologists.

The meeting facilitated the selection of five common and abundant bird species present across various study zones for tracking their mobility patterns using GPS or Sigfox biologging. While bird migration and mobility have been studied on large scales, there’s limited data on the daily mobility of resident species and the impact of the landscape on their movements. Understanding these aspects is vital to determine the role different species play in transmitting pathogens like the West Nile virus across areas, such as from marshes or rice fields to peri-urban or urban zones.

Wild birds, being primary hosts of the virus, play a crucial role in its spread, thereby shaping the epidemiology of the disease. Assessing how they connect habitats and transfer pathogens is particularly crucial in human-altered landscapes where pathogen spillover between birds and humans can be facilitated. The lack of detailed information in the dissemination process of zoonotic pathogens undermines risk assessments and management plans. A key goal of WP5 is to quantify the mobility of various host species to develop a spatially-explicit approach to wildlife epidemiology.