A comprehensive international analysis has revealed the complex interplay of factors driving the spread of West Nile Virus (WNV), a mosquito-borne disease increasingly impacting temperate regions, particularly in Europe. The study underscores the critical role of climate, land use and socioeconomic conditions in the virus’s transmission.
Published in One Health, the research is an umbrella review integrating 23 systematic reviews and meta-analyses, examining over 1,900 studies to pinpoint the environmental, ecological, and individual determinants fueling WNV circulation.
The findings demonstrate a clear link between rising temperatures, especially during spring and summer, and both the proliferation of Culex mosquitoes – the primary vectors of WNV – and the virus’s replication within them. This process is further intensified by milder winters, creating a longer transmission season.
Extreme weather events also play a significant role. Droughts and intense rainfall events alter ecosystem dynamics, creating breeding grounds for mosquitoes and concentrating bird populations – natural reservoirs of the virus – around remaining wetland areas. This increased proximity elevates the risk of transmission to humans as mosquitoes seek new blood sources.
Changes in land use, including urbanization, intensified agriculture, and ecosystem degradation, are also closely associated with mosquito density and viral circulation. Areas with irrigation, wetlands, and urban environments with deteriorating infrastructure show a heightened risk of WNV transmission.
Socioeconomic Factors and Vulnerability
The study highlights that socioeconomic factors are essential determinants of vulnerability to WNV. Limited access to resources, lack of education, and a low perception of risk contribute to reduced adoption of preventative measures, increasing exposure to the mosquito vector.
Certain occupational groups – including agricultural workers, veterinarians, military personnel, and laboratory staff – face a higher probability of infection due to their outdoor activities or contact with potentially infected animals.
“Understanding how climate, territory, ecosystems, and social conditions interact is fundamental to anticipating outbreaks and strengthening surveillance systems,” says Clara Bermúdez-Tamayo, a researcher involved in the study. “The evidence demonstrates that the One Health approach – integrating human, animal, and environmental health – is not just recommended, it’s essential for protecting public health against vector-borne diseases like West Nile Virus.”
The Expanding Threat in Europe
Recent research confirms the growing threat of WNV in Europe. A study published in ScienceDirect projects up to a five-fold increase in WNV risk across Europe between 2040 and 2060, depending on the geographical region and climate scenario.
This expansion is not solely attributable to climate change. An analysis published in Nature demonstrates that while the area ecologically suitable for WNV circulation has increased significantly since 1901, this increase would have been far less pronounced without the effects of long-term climate trends. The study emphasizes that both historical changes in population density and climate change have contributed to the heightened risk of WNV circulation in Europe.
a recent early warning system implemented in northern Greece, covering the period 2020-2024, demonstrates the feasibility of proactive monitoring and risk assessment, as reported by Nature.
The Need for Integrated Prevention Strategies
The authors of the One Health study emphasize the need for integrated prevention and control strategies that incorporate environmental information, veterinary surveillance, and epidemiological monitoring. They also call for educational initiatives and awareness campaigns targeted at the public and high-risk groups.
The research also highlights the urgency of conducting longitudinal studies to better understand the long-term effects of climate change and landscape transformation on WNV transmission and the emergence of other pathogens. This requires a collaborative, multidisciplinary approach, bringing together expertise in physics, earth sciences, ecology, conservation biology, health economics, and public health.
The study was framed within the Off-Oceans for Future project, led by the Faculty of Physics at Complutense University of Madrid, and developed in collaboration with researchers from the ibs.GRANADA, CSIC–Doñana, the Andalusian School of Public Health, and the University of Granada. This collaborative effort underscores the importance of a holistic approach to understanding and mitigating the risks posed by vector-borne diseases in a changing world.
