The Natural Park of Aiguamolls de l’Empordà: an open-air lab to understand the transmission of West Nile virus
The Empordà Wetlands (Aiguamolls de l’Empordà in catalan) are not only a paradisiacal enclave or a refuge for migratory birds, but also an open-air laboratory where, in collaboration with the Natural Park and the Mosquito Control Service of Badia de Roses and Baix Ter, the circulation of West Nile virus among birds, mosquitoes, and humans is studied.
Citizen science to understand disease transmission networks
At Mosquito Alert, we promote the use of citizen science to identify and monitor disease-transmitting mosquitoes. With the data provided by the public, besides implementing an alert system (when mosquitoes are discovered in areas where their presence was previously unknown), we also analyze these data scientifically to study the relationship between people and mosquitoes.
With this goal, we are part of several research projects, including E4Warning, coordinated by Frederic Bartumeus, co-director of Mosquito Alert and researcher at CEAB-CSIC, which aims to develop early warning systems against mosquito-borne diseases in endemic and emerging areas.
One of the tasks in this project is to combine citizen science data with field data to enable predictions about mosquito-borne diseases, such as West Nile fever.
What connections exist between mosquitoes, birds, and humans?
Migratory birds that stay in wetlands can be infected with West Nile virus. The infection can be transmitted from bird to bird through mosquito bites, and infect other animals, including humans, through bites of the common mosquito (Culex pipiens). In this case, it is not an invasive mosquito, but a native mosquito that transmits the virus.
One key to predicting virus spread is understanding how many mosquitos they are, which species, when, and where. To deepen this, the scientific team studies the biting network by monitoring and studying the mosquitoes present throughout the season at the Natural Park.
Using traps to capture adult mosquitoes, resting traps, and aspirators designed and provided by Nathan Burkett-Cadena, a renowned researcher from the University of Florida, mosquitoes are sampled and then species are identified along with their abundance. Specifically, the team counts how many are females and how many have fed on blood. In the laboratory, they analyze whose blood the mosquito ingested through genetic testing. This allows reconstructing the interaction network between species and detecting possible transmission routes.
Birds as virus reservoirs
Many migratory birds can act as natural reservoirs of the virus, keeping it active during their routes. For this reason, field surveys are carried out to identify the birds in the area, complemented by acoustic devices (such as AudioMoth) to record their songs, which are automatically identified with artificial intelligence (BirdNet). GPS tracking is also done on some birds to understand their movements and include it in predictions.
This research also considers environmental data such as temperature, humidity, water use, and how human activity produces differential exposure to diseases and contributes to the spread of invasive mosquitoes and diseases. All this helps understand how and why the virus can jump from a natural environment to a more urban one.
Towards an early warning system
All these data are integrated into computational models that simulate risk scenarios and anticipate possible outbreaks. Through the E4Warning project, this research at the Aiguamolls de l’Empordà represents a step forward toward building more accurate and integrated early warning systems. By combining environmental data, bird monitoring, mosquito sampling, and citizen science, we can better understand how diseases are transmitted. It is an example of how collaboration between research, territory management, and social participation can respond to global health and environmental change challenges.
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