A recent study, published in The Lancet Regional Health – Europe, sheds light on the short-term effects of temperature and precipitation on the incidence of West Nile Neuroinvasive Disease (WNND) in Europe. Conducted by researchers from the E4Warning partners from the Barcelona Supercomputing Center (BSC) and international collaborators, the study utilized a nine-year dataset (2014–2022) to analyze 3,437 WNND cases across 20 European countries.

To estimate the association between lagged meteorological variables and WNND cases, the study employed a space-time-stratified case-crossover design. This design treats each case as its control, comparing exposures during the “hazard period” (the weeks before symptom onset) to exposures in comparable “reference periods.” Cases and controls were matched within the same region, calendar month, and year, as well as by the day of the week, enabling precise control of confounding factors such as geography, long-term trends, and seasonality.

For each case, weekly mean temperature and cumulative precipitation were attributed to the 8 weeks preceding the symptom onset day and matched control days. For instance, if a case occurred on May 17, 2019, in a given region, control days were selected from other Fridays in the same month and year. This method allowed researchers to infer associations between meteorological conditions and WNND incidence.

Meteorological data were obtained from the ERA5-Land climate reanalysis database, produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). Researchers retrieved gridded daily mean temperature and daily cumulative precipitation data for the European continent over the entire study period (2014–2022). ERA5-Land provides atmospheric and land-surface variables with a spatial resolution of approximately 9 km × 9 km. To align with epidemiological data, daily meteorological data were spatially averaged at the NUTS3 level.

Key Findings:

• Temperature and Precipitation as Drivers: Weekly mean temperatures exceeding 25°C (the 90th percentile) were associated with 36.4% of WNND cases, with the strongest effect observed two weeks before symptom onset. Similarly, weekly cumulative precipitation above 40 mm contributed to 13.1% of cases, with a delayed peak effect three weeks before symptom onset.
• Regional Variation: The study highlighted consistent effects of temperature across regions but noted moderate variability in precipitation’s impact, reflecting differences in local ecosystems and mosquito ecology.
• Implications for Early Warning Systems: The findings underline the potential of integrating meteorological data into early warning systems. These systems could enhance preparedness for WNV outbreaks, particularly in areas lacking robust vector and host surveillance infrastructure.

Broader Implications:

This study reinforces the link between climate variability and the transmission of mosquito-borne diseases, emphasizing the need for a One Health approach to address the complex interactions between climate, ecosystems, and human health. The results provide actionable insights for tailoring early warning systems and vector control strategies to mitigate the growing burden of WNV outbreaks in Europe.

For more details, check out the paper: Moirano, G., Fletcher, C., Semenza, J. C., & Lowe, R. (2025). Short-term effect of temperature and precipitation on the incidence of West Nile Neuroinvasive Disease in Europe: a multi-country case-crossover analysis. The Lancet Regional Health – Europe, 48, 101149. https://doi.org/10.1016/j.lanepe.2024.101149

And in the E4Warning Zenodo repository: https://zenodo.org/records/14383572

Our partner and WP leader, Rachel Lowe, ICREA Research Professor and Global Health Resilience (GHR) Group Leader at the Barcelona Supercomputing Center (BSC), was recently interviewed by HERA (Health Emergency Preparedness and Response Authority) and featured on their website: https://ec.europa.eu/newsroom/hera/items/852413/en

HERA is an EU body established to strengthen Europe’s ability to anticipate and respond to health emergencies, particularly in the wake of the COVID-19 pandemic. It aims to ensure the provision of critical medical countermeasures and enhance Europe’s readiness for future health threats.

In the interview, Rachel Lowe discusses the intricate connections between climate change and the outbreaks of climate-sensitive infectious diseases, exploring why these outbreaks are increasing and spreading to new regions, particularly in Europe. She also explains how shifting climate patterns could influence emergency preparedness and response strategies, highlighting the need for proactive, integrated approaches. She shared insights into specific climate-sensitive diseases that pose a potential threat to the EU, including dengue, chikungunya, and West Nile virus, and discussed ongoing efforts like the development of the EpiOutlook platform within the IDAlert project, which is part of the European Climate-Health Cluster. This platform aims to provide early warnings of climatic suitability for various infectious diseases in Europe. They also track the impact of climate change on these diseases in the Lancet Countdown in Europe collaboration.

As part of E4Warning, Professor Lowe also elaborated on her work in developing decision support tools like the D-MOSS (Dengue forecasting Model Satellite-based System) for dengue in endemic regions in collaboration with HR-Wallingford, as well the efforts on integrating different data sources such as citizen science initiatives like Mosquito Alert, which could enhance the monitoring and management of disease vectors across Europe, providing critical support for future public health interventions.

For more details, read the full interview on the HERA website and gain valuable insights into how E4Warning and its partners are addressing the growing challenges posed by climate-sensitive diseases in Europe.

E4Warning participated in the high-level conference “Research Perspectives on the Health Impacts of Climate Change,” organized by the Directorate-General for Research and Innovation (DG RTD) of the European Commission. This event, held in Brussels on February 19th and 20th, 2024, aimed to highlight the crucial nexus between climate change and global health issues.

Chloe Fletcher, a PhD candidate from the Global Health Resilience group at the Barcelona Supercomputing Center (BSC), attended the conference. Her research focuses on developing statistical models for predicting outbreaks of climate-sensitive infectious diseases, such as dengue and leptospirosis. Fletcher presented a poster titled “A Generalized Modelling Framework for Dengue Early Warning Systems in South and Southeast Asia,” a collaborative effort involving Ramy Hoek Spaans (BSC), Sophie Belman (BSC), Chloe Fletcher (BSC), Quillon Harpham (HRW), Gina Tsarouchi (HRW), and Rachel Lowe (BSC), all contributing to the E4Warning project.

This study aims to broaden the successful application of the Dengue Forecasting Model Satellite-based System (D-MOSS), originally implemented in Vietnam, to include Sri Lanka and Malaysia. By employing a Bayesian modeling approach and contrasting it with the conventional practices of dengue outbreak monitoring in each nation, the research seeks to identify which dengue predictors remain consistent or vary across these diverse regions.

The goal is to establish a universally applicable template for developing dengue early warning systems. The D-MOSS platform, which underpins this forecasting system, is managed by HR Wallingford. A key ambition of E4Warning is to collaborate intimately with local partners to deliver actionable data visualizations, thereby enabling an informed, data-driven approach to dengue management.

You can view the summaries of other posters presented during the conference at this link.

The early warning system for dengue fever in Vietnam, developed by D-MOSS as part of the E4Warning initiative, has been highlighted as a significant success story during the launch of the World Meteorological Organization’s (WMO) “Climate Services for Health” report launched the past 2th November 2023. Rachel Lowe from the Barcelona Supercomputing Center (BSC) represented the project, elaborating on the vital work performed by E4Warning.

The presentation underscored how this advanced system is making strides in public health by providing early warnings of dengue fever outbreaks. By harnessing climate data and predictive modeling, the system is aiding Vietnam in taking preemptive measures to mitigate the impact of this vector-borne disease, thereby safeguarding communities and strengthening the resilience of health systems.

The latest World Meteorological Organization’s (WMO) State of Climate Services report delivers a compelling message about the intricate connection between our changing climate and public health. The report acts as a clarion call, highlighting the dire need for precise climate information and services to bolster the health sector amid escalating threats from extreme weather events, evolving disease patterns, and the looming specter of food and water scarcity.

Prof. Petteri Taalas, WMO Secretary-General, brings to the forefront the widespread occurrence of heatwaves across the globe, further intensified by the imminent onset of El Niño. This scenario sets a backdrop for heightened temperature records, amplifying the urgency for increased investment and collaborative efforts to elevate the role of climate science. By doing so, health partners can gain critical support in times when our climate’s unpredictability takes a tangible toll on human health.

In alignment with Prof. Taalas’s observations, WHO Director-General Dr. Tedros Adhanom Ghebreyesus defines the climate crisis as an escalating health crisis. He underlines the vital need for access to high-quality climate services within the health sector to counteract the perilous effects of climate change on human well-being.

Despite this clear need, the report reveals a gap: climate data often does not permeate health decision-making processes as it should. This disconnect points to an essential requirement for improved early warning systems, especially since disaster events are anticipated to surge, with less-prepared countries facing significantly higher mortality rates.

The focus then shifts to the underestimation of extreme heat’s health impacts. Highlighting the efforts of the Early Warnings for All initiative, the report underscores the necessity to expand heat warning services, which are currently absent in many vulnerable regions.

Ultimately, the WMO report connects the dots between the adverse effects of climate change on various aspects of health — from the quality of the air we breathe to the nutritional security of our food and the control of infectious diseases. It’s a comprehensive wake-up call for cross-sectoral action, aiming to fortify the health community against the multifaceted challenges posed by a warming world. This post serves to emphasize that climate action is not just an environmental imperative but a crucial facet of global health strategy.

Tangible solutions

The World Meteorological Organization’s (WMO) State of Climate Services report doesn’t just outline the challenges; it showcases tangible solutions through success stories where climate services have made significant inroads in health outcomes. One such example is the early warning system for dengue in Vietnam, which was presented as a beacon of the potential benefits of climate services for health. This system, alongside other initiatives from Africa, Europe, the Pacific, and the Pan-American region, represents the strides being made in marrying meteorological insights with health sector needs.

The State of Climate Services report can be downloaded here.