Mosquito-borne diseases such as West Nile virus (WNV), chikungunya, and dengue are spreading more widely and for longer durations across Europe, with health authorities warning that changing climate patterns are fueling both the intensity and reach of recent outbreaks.

These developments mark a turning point in Europe’s ongoing battle against mosquito-borne diseases, health authorities and researchers have told Medscape Medical News. Not only are endemic disease risks growing, but climate change is opening the door to the arrival of new vectors and pathogens — posing challenges for surveillance, prevention, and medical preparedness across the continent.

According to a recent press release from the European Centre for Disease Prevention and Control (ECDC), by the end of August 2025, Europe had reported 290 cases of locally acquired chikungunya virus infection — compared with just one case in all of 2024. Cases of other mosquito-borne illnesses have also spiked: 304 locally acquired cases of dengue were reported in 2024, exceeding the 275 cases recorded in the previous 15 years combined. Meanwhile, WNV case numbers as of early August 2025 were slightly above the past decade’s average.

Recent exponential growth of mosquito-borne diseases increases the risk for epidemicity in the coming years, Jan C. Semenza, PhD, project manager at the Department of Epidemiology and Global Health at Umeå University, Umeå, Sweden, told Medscape Medical News.

While disease-carrying mosquitoes could reach as far north as southern Scandinavia, Semenza warned that widespread outbreaks are more likely in southern European countries like Italy and Croatia, where invasive mosquitoes have already gained a foothold.

Semenza’s recent study, which tracked the spread of mosquito-borne diseases in Europe over the past 35 years, found that every 1 °C increase in average summer temperature raised the risk for outbreaks by 55%. The study projected that under worst-case climate scenarios, the risk for dengue or chikungunya outbreaks could increase almost fivefold by the 2060s.

With these threats mounting, Semenza said, the need for vaccine intervention is likely to grow. The rapid growth of these diseases, fueled by warming climates, means that people may soon need vaccines to travel to affected countries. National vaccination plans may also become necessary in the future.

However, vaccines are not a near-term solution at a national level, according to Caterina Rizzo, MD, MPH, professor of hygiene and preventive medicine at the University of Pisa, Pisa, Italy, due to limitations in the available vaccines. However, she told Medscape Medical News that such campaigns “will probably happen” in future decades.

Coordinated Efforts to Control the Spread

European health authorities are ramping up efforts to contain outbreaks. Tamás Bakonyi, DVM, PhD, DSc, ECDC’s principal expert on vector-borne and zoonotic diseases, told Medscape Medical News that the European Union (EU) is focusing on early detection, strengthened surveillance, and boosting public awareness.

The newly established European Union Reference Laboratory for Public Health on Vector-Borne Viral Pathogens has been supporting national laboratories since early 2025. Its initiatives include sharing reference materials and diagnostics, facilitating training programs, organizing twinning visits, and conducting external quality assessments — all aimed at harmonizing laboratory practices and surveillance across member states.

Additionally, countries continue to report cases of mosquito-borne diseases to the ECDC via the European surveillance portal for infectious diseases (EpiPulse) to track both locally acquired and imported infections. Monitoring of vector species through the ECDC-European Food Safety Authority VectorNet project — ongoing since 2014 — helps map changes in mosquito populations across Europe.

“At the EU level, harmonized case reporting through the ECDC, coordinated vector monitoring, and seasonal risk assessments support timely cross-border responses,” Bakonyi said.

In July 2025, the ECDC published new public health guidelines for curbing the spread of locally acquired mosquito-borne diseases, detailing strategies for surveillance, prevention, preparedness, and control actions according to risk level.

National Response: The Situation in Italy

On the ground, regional authorities in Italy have kept the situation “under control,” thanks to a long history of responding to outbreaks, Rizzo said. She noted that since the country’s experience with WNV began in 2010, outreach efforts by healthcare professionals, governmental authorities, and the media have helped make the population aware of both the risks and protective measures.

But this level of readiness is not guaranteed everywhere. Rizzo cautioned that while outbreaks have so far occurred mainly in well-prepared northern regions, central and southern Italy may be more vulnerable if the disease spreads further, due to varying levels of preparedness.

A greater threat, she warned, could emerge as new mosquito species — such as Aedes aegypti, known for transmitting yellow fever — expand into Europe. The ECDC has already confirmed that A aegypti is now established in Cyprus.

Addressing Gaps and Building Preparedness

Rizzo highlighted a need for greater coordination among local municipalities in Italy, as disparate resources and approaches mean some regions are less able to implement effective vector control measures. Sharing resources and best practices at the local level, she said, could significantly improve on-the-ground response efforts.

Sustained funding throughout the year is also crucial, Rizzo argued. With mosquito larvae able to survive in cold-weather refuges, control measures during winter can be just as important as in summer to reduce the risk for future outbreaks.

From a broader perspective, Semenza recommended developing platforms that can monitor both population movements from endemic areas and map areas at climatic risk for transmission — tools that will be vital in helping healthcare systems anticipate and respond to new outbreaks.

Individual Protection and Public Health Advice

Prevention at the individual level also plays a key role. As Semenza noted, lifestyle factors can have a significant impact on disease transmission. He observed differences in dengue rates between northern Mexico and southern Texas, for example, which may be attributed to differences in the amount of time spent outdoors and exposure to mosquitoes.

Semenza advised using mosquito repellent, eliminating standing water around homes, and other control measures to reduce the presence and breeding of mosquitoes.

Bakonyi added further recommendations: wearing long sleeves and trousers, especially at dawn and dusk when mosquitoes are most active, and using bed nets or staying in screened or air-conditioned rooms.

“Travelers returning from regions where diseases like dengue or chikungunya are circulating should continue these precautions for at least 3 weeks to avoid introducing viruses into areas where competent mosquito vectors are present,” Bakonyi said.

Semenza reported having no relevant financial relationships. Rizzo reported participation on the advisory board of the chikungunya vaccines, Ixchiq and Vimkunya.

Annie Lennon is a medical journalist. Her writing appears on Medscape Medical News, WebMD, and Medical News Today, among other outlets.