Vector-borne diseases

Climate change alters the distribution and activity of disease-carrying vectors like mosquitoes, ticks, and sandflies in Europe. Warmer temperatures have enabled outbreaks of dengue, chikungunya, West Nile fever, and tick-borne diseases in new regions. Future warming is expected to expand vectorborne disease risks northward, especially under high emissions scenarios.

Health issues

Climate change is changing the way some diseases are transmitted in Europe, especially those spread by vectors like ticks and mosquitos. Higher temperatures, changes in rainfall, milder winters, and shifts in ecosystems affect the activity, numbers, and areas where these vectors live. This means that the diseases they carry can appear in areas where they were rare or never seen before. The European Centre for Disease Prevention and Control (ECDC) provides regular updates on the geographic distribution of these vectors in Europe, as well as on the occurrence of the diseases they transmit in EU/EEA.

The following tables are a non-exhaustive list of vector-borne diseases divided into mosquito and tick-borne diseases.

Mosquito-borne diseases

Disease	Vectors (Family/Species)	Health Issues (Symptoms & Complications)
Chikungunya virus disease	Mainly Aedes aegypti, Aedes albopictus	Sudden high fever, severe joint pain (often in hands and feet), muscle pain, headache, nausea, fatigue, and rash. Joint pain can persist for months or years.
Dengue	Mainly Aedes aegypti, Aedes albopictus	High fever, severe headache, pain behind the eyes, joint and muscle pain, nausea, vomiting, skin rash. Severe dengue can cause bleeding, organ damage, and plasma leakage.
Japanese encephalitis	Culex spp., others	Most infections are mild or asymptomatic. Severe cases include sudden onset of headache, high fever, disorientation, coma, seizures, and paralysis. Can cause permanent neurological damage.
Malaria	Anopheles spp.	Fever, chills, sweats, headache, nausea, vomiting, body aches, and general malaise. Severe malaria can cause anaemia, respiratory distress, organ failure, and cerebral complications.
Rift Valley fever	Various (inc. Aedes spp., Culex spp.)	Most cases are mild with fever, muscle pain, and headache. Severe cases can develop eye disease, encephalitis, or haemorrhagic fever with bleeding and liver damage.
Sindbis virus infection	Culex spp., Culiseta spp.	Mild fever, malaise, rash, and joint pain. Joint pain typically affects wrists, ankles, knees, and fingers, and may last several months. Most cases are self-limiting.
West Nile virus infection	Mainly Culex pipiens	Most people are asymptomatic. Symptomatic cases show fever, headache, body aches, joint pain, vomiting, diarrhoea, or rash. Severe cases cause encephalitis, meningitis, or paralysis.
Yellow fever	Aedes aegypti	Initial phase: fever, muscle pain, headache, shivers, loss of appetite, nausea, and vomiting. Severe phases: jaundice, bleeding, shock, organ failure, particularly affecting the liver and kidneys.
Zika virus disease	Mainly Aedes aegypti, Aedes albopictus	Most infections are asymptomatic. When symptoms occur mild fever, rash, conjunctivitis, muscle and joint pain, and headache. Infection during pregnancy can cause severe birth defects.

Source: https://www.ecdc.europa.eu

Tick-borne diseases

Disease	Vectors (Family/Species)	Health Issues (Symptoms & Complications)
Lyme borreliosis	Ixodes ricinus I. persculcatus	Early stage: expanding red rash (erythema migrans), fever, headache, fatigue, muscle and joint aches. Clinical manifestation in later stages vary widely: severe headaches, neck stiffness, arthritis with joint swelling, nerve pain, heart palpitations, and neurological problems including facial paralysis.
Tick-borne encephalitis (TBE)	Ixodes ricinus	First phase: fever, fatigue, headache, muscle pain, and nausea. Second phase (in severe cases): meningitis or encephalitis with high fever, severe headache, stiff neck, confusion, sensory disturbances, paralysis, and seizures.
Crimean-Congo haemorrhagic fever (CCHF)	Hyalomma marginatum	Sudden onset of fever, muscle aches, dizziness, neck pain, headache, sore eyes, and sensitivity to light. Later symptoms include nausea, vomiting, diarrhoea, abdominal pain, and severe bleeding from skin, nose, mouth, and internal organs. High fatality rate in severe cases.

Disease

Vectors (Family/Species)

Health Issues

(Symptoms & Complications)

Lyme borreliosis

Ixodes ricinus

I. persculcatus

Early stage: expanding red rash (erythema migrans), fever, headache, fatigue, muscle and joint aches. Clinical manifestation in later stages vary widely: severe headaches, neck stiffness, arthritis with joint swelling, nerve pain, heart palpitations, and neurological problems including facial paralysis.

Tick-borne encephalitis (TBE)

Ixodes ricinus

First phase: fever, fatigue, headache, muscle pain, and nausea. Second phase (in severe cases): meningitis or encephalitis with high fever, severe headache, stiff neck, confusion, sensory disturbances, paralysis, and seizures.

Crimean-Congo haemorrhagic fever (CCHF)

Hyalomma marginatum

Sudden onset of fever, muscle aches, dizziness, neck pain, headache, sore eyes, and sensitivity to light. Later symptoms include nausea, vomiting, diarrhoea, abdominal pain, and severe bleeding from skin, nose, mouth, and internal organs. High fatality rate in severe cases.

Source: https://www.ecdc.europa.eu

Observed effects

Climate change is no longer a future threat, it is a current one, and it is actively reshaping the landscape of infectious diseases across Europe (EEA, 2022). We are witnessing a "new normal" where tropical diseases are being locally transmitted in Europe. Invasive vectors, such as the Asian tiger mosquito (Aedes albopictus), are now established across the continent, pushing northward and into higher altitudes where they could not previously survive (World Mosquito Day 2025: Europe sets new records for mosquito-borne diseases).

The evidence is clear: record-breaking numbers of locally-acquired cases of West Nile virus infection and chikungunya virus disease are surfacing in regions once considered safe (Wadman, 2025). This shift is driven by biological adaptation: mosquitoes are developing "cold-hardiness" to survive European winters, while viral pathogens are mutating to spread more efficiently within our local environments (Delwel and Mordecai, 2025). To protect European citizens, political urgency and integrated surveillance are now paramount to managing these expanding health risks (Regulation (EU) 2022/2371 on serious cross-border threats to health).

Mosquito-borne diseases

Disease	Endemic in EU?	Observed Effects (Surveillance 2019–2025)
Chikungunya virus disease	No	Climate warming plays a significant role in Aedes albopictus establishment in Europe, with each 1°C rise in mean summer temperature associated with accelerated outbreak onset (Farooq et al. 2025). We are seeing more outbreaks and with higher number of cases than before.
Dengue	No	Experiencing a rapid surge in autochthonous transmission, with over 300 locally acquired cases in 2024. We are seeing more outbreaks and with higher number of cases than before.
Japanese Encephalitis	No	No local human cases confirmed in Europe to date. Spread of the virus within the EU would likely occur through the movement of wild birds, pigs and mosquitoes (Gossner et al. 2024).
Malaria	No	Predominantly travel-associated cases. Sporadic locally-acquired transmission occasionally documented in southern Europe (e.g. Greece) during warm periods with competent Anophleles vectors present, though sustained endemic transmission has not been re-established (ECDC surveillance reports: https://www.ecdc.europa.eu/en/malaria).
Rift Valley Fever	No	Primarily poses a threat to livestock in endemic African regions. No transmission of the virus has been reported in mainland Europe. Human imported cases are seldom reported in mainland Europe, among travelers returning from endemic areas or occupational laboratory exposures. European mosquito competence studies indicate potential for transmission if virus is introduced (Nielsen et al. 2020).
Sindbis Virus Infection	Yes (Focal)	Endemic primarily to Northern Europe (Finland, Sweden), where it follows a unique seven-year cyclical outbreak pattern. It is most prevalent in late summer, coinciding with mosquito activity (https://www.ecdc.europa.eu/en/sindbis-fever/facts).
West Nile Virus Infection	Yes	In Europe, West Nile virus (WNV) is an emerging public health threat that has seen a significant spatial expansion and an increase in the frequency of outbreaks over the last two decades. Recent research highlights that anthropogenic climate change has been a critical driver of this expansion by increasing the ecological suitability of the continent for WNV circulation, particularly through rising temperatures that enhance mosquito transmission potential. This shifting environmental landscape, combined with changes in land use and human population density, has notably increased the population at risk of exposure across Europe (Erazo et al. 2024).
Yellow Fever	No	Not established in Europe. Risk of autochthonous transmission is considered negligible. Also, the primary vector, Aedes aegypti, has a limited presence in Europe. All cases in mainland Europe remain exclusively travel-related with no documented local transmission (https://www.ecdc.europa.eu/en/yellow-feve r).
Zika Virus Infection	No	In Europe, Zika virus is predominantly an imported, travel-associated disease with very rare instances of local mosquito-borne transmission. The risk of widespread establishment remains low due to environmental constraints on its primary mosquito vectors (Kerlik et al. 2025).

Tick-borne diseases

Disease	Endemic in EU?	Observed Effects (Surveillance 2019–2025)
Lyme Borreliosis	Yes (Widespread)	In Europe, Lyme borreliosis is the most prevalent tick-borne disease, showing an upward trend in incidence in Northern and Eastern countries (Burn et al. 2023; Davidson et al. 2025). It is widely distributed across the continent, with the highest burden reported in Central and Northern Europe. The disease's impact is characterized by a high frequency of healthcare consultations and a substantial socio-economic burden (Willems et al. 2023; Brestrich et al. 2025).
Tick-borne Encephalitis (TBE)	Yes (Focal)	Concentrated primarily in Central, Eastern, and Northern Europe. The virus is expanding into new regions, with several areas reporting their first human cases or an increase in infection rates in recent years (https://www.ecdc.europa.eu/en/news-events/tick-borne-encephalitis-tbe-europe-new-maps-published).
Crimean-Congo Haemorrhagic Fever (CCHF)	Yes (Focal)	Historically endemic to the Balkans, Russia, and Ukraine, but now emerging in Southwestern Europe (Spain and Portugal).

Disease

Endemic

in EU?

Observed Effects

(Surveillance 2019–2025)

Lyme Borreliosis

Yes (Widespread)

In Europe, Lyme borreliosis is the most prevalent tick-borne disease, showing an upward trend in incidence in Northern and Eastern countries (Burn et al. 2023; Davidson et al. 2025). It is widely distributed across the continent, with the highest burden reported in Central and Northern Europe. The disease's impact is characterized by a high frequency of healthcare consultations and a substantial socio-economic burden (Willems et al. 2023; Brestrich et al. 2025).

Tick-borne Encephalitis (TBE)

Yes (Focal)

Concentrated primarily in Central, Eastern, and Northern Europe. The virus is expanding into new regions, with several areas reporting their first human cases or an increase in infection rates in recent years (https://www.ecdc.europa.eu/en/news-events/tick-borne-encephalitis-tbe-europe-new-maps-published).

Crimean-Congo Haemorrhagic Fever (CCHF)

Yes (Focal)

Historically endemic to the Balkans, Russia, and Ukraine, but now emerging in Southwestern Europe (Spain and Portugal).

Projected effects

Tiger mosquito climatic suitability in 2041–2070 under a high-emission scenario

(Click the map to see the interactive version)

The Tiger Mosquito Climatic Suitability index is relevant to human health. The tiger mosquito (Aedes albopictus) is an invasive species from south-east Asia favoured by a warmer climate and represents a serious threat as it transmits vector-borne diseases such as dengue and chikungunya. Environmental factors, among which weather conditions, affect both the potential presence and seasonal activity of the tiger mosquito. Here an example for the mid‑century (2041–2070) projections of Tiger mosquito suitability in EU countries under a high‑emission scenario (RCP 8.5).
Source: Copernicus Climate Change Service (C3S)

Rising temperatures, milder winters and shifting precipitation are already lengthening mosquito seasons and expanding Aedes and Culex populations in Europe. On Mosquito day (Aug 20),  2025, ECDC stated that hotter and longer summers and changes in rainfall are creating a “new normal” of longer and more intense transmission seasons for mosquito-borne diseases, with West Nile virus and chikungunya virus being detected in new areas and outbreaks reaching record numbers (https://www.ecdc.europa.eu/en/news-events/world-mosquito-day-2025-europe-sets-new-records-mosquito-borne-diseases).  ECDC’s guidance on Aedes-borne diseases, likewise, warns that climate change will lengthen favourable environmental periods for Aedes  mosquitoes, raising the potential for dengue, chikungunya virus disease and Zika virus disease outbreaks in the European continent.

The Lancet Countdown Europe reports that climatic suitability is increasing for West Nile virus, dengue virus, chikungunya virus, Zika virus and Plasmodium parasites (causing malaria), suggesting that warming climates will allow these pathogens to persist farther north and for longer each year (Van Daalen et al. 2024).

But climate change is not only affecting mosquito-borne diseases. WHO Europe’s assessment of Lyme borreliosis shows that ticks have already expanded to higher latitudes and altitudes in Europe and that future warming is likely to facilitate further spread while reducing occurrence in areas that become too hot and dry (https://www.who.int/publications/i/item/9789289022910).

Policy responses

EU policy on vector-borne diseases (VBDs) has progressively shifted from a largely reactive approach—focused on responding to outbreaks as they occur—to a more proactive and integrated framework that reflects the “new normal” of climate-driven health risks. Rising temperatures, biodiversity loss, and ecological disruption, along with globalisation, are expanding the geographic range and seasonal transmission windows of vector-borne pathogens. In this context, the EU has increasingly embedded VBD preparedness within the broader vision of the European Health Union, which aims to strengthen long-term resilience and coordinated action across Member States rather than relying on temporary containment measures (https://commission.europa.eu/topics/public-health/european-health-union_en).

A key pillar of this evolving strategy is improved preparedness through investment in innovation and health security, such as an EU joint action for the scaling up of Member States’ national systems for vector threat detection and control capacities. This joint action will establish interdisciplinary programmes to monitor vector distribution and population dynamics and will develop and implement countermeasures for the control of disease-transmitting vectors, including physical, biological, and chemical methods, complemented by public outreach campaigns.

At the operational level, EU policy is also advancing toward integrated vector surveillance and control. Rather than focusing only on human clinical cases, the EU promotes a One Health-informed approach that incorporates animal surveillance (through The European Food Safety Authority (EFSA) mission), and entomological monitoring. The ECDC-EFSA funded project VectorNet plays a central role in collecting and sharing data on mosquito, tick, and other vector populations across Europe, enabling earlier risk detection and more targeted interventions before outbreaks spread widely (https://www.vectornetdata.org/).

Scientific coordination between EU agencies further strengthens this integrated framework. EFSA, particularly through its Panel on Animal Health and Welfare, provides independent scientific advice on zoonotic vector-borne diseases that affect animals (https://www.efsa.europa.eu/en/topics/topic/vector-borne-diseases). EFSA works closely with ECDC to share surveillance information and both agencies jointly administer the One-Health VectorNet network and project on vectors of veterinary and public health relevance.

Together, based on data collected by Member States, EFSA and ECDC join forces to assess the emergence of West Nile virus in Europe and produce joint monthly reports on infections in humans and animals, supporting evidence-based policymaking and reinforcing cross-sectoral cooperation at the heart of the EU’s VBD strategy.

In parallel to these institutional and regulatory developments, the EU is also strengthening its scientific and operational foundations for climate‑related health threats through the European Climate–Health Cluster (Climate Health), a Horizon Europe cooperation that brings together six major research and innovation projects: BlueAdapt, CATALYSE , CLIMOS, HIGH Horizons, IDAlert and TRIGGER. Working collectively, these projects generate evidence, data, surveillance tools, and early‑warning capacities that directly support EU preparedness for vector‑borne and other climate‑sensitive diseases. The Cluster promotes synergies across environmental, climate, and health research communities, improves science‑policy translation, and develops harmonised indicators and modelling approaches that help anticipate emerging risks rather than respond to them reactively. By feeding cutting‑edge scientific knowledge into initiatives such as the European Health Union, HERA, and the EU Strategy on Adaptation to Climate Change, the Climate–Health Cluster acts as a bridge between research, policy, and practice—strengthening the EU’s ability to forecast threats, guide targeted interventions, and build long‑term resilience in a rapidly changing climate.

References

Brestrich, Gordon, Joanna Diesing, Nils Kossack, et al. 2025. “Excess Healthcare Costs and Resource Utilisation of Lyme Borreliosis in Germany: A Propensity Score–Matched Cohort Study.” Zoonoses and Public Health 72 (1): 23–31. https://doi.org/10.1111/zph.13180
Burn, Leah, Thao Mai Phuong Tran, Andreas Pilz, et al. 2023. “Incidence of Lyme Borreliosis in Europe from National Surveillance Systems (2005–2020).” Vector-Borne and Zoonotic Diseases 23 (4): 156–71. https://doi.org/10.1089/vbz.2022.0071
Davidson, Alexander, Julie Davis, Gordon Brestrich, Jennifer C. Moisi, Luis Jodar, and James H. Stark. 2025. “Lyme Borreliosis Incidence Across Europe, 2015–2023: A Surveillance-Based Review and Analysis.” Vector-Borne and Zoonotic Diseases 25 (10): 569–79. https://doi.org/10.1177/15303667251363125
Delwel, Isabel O., and Erin A. Mordecai. "Molecules to spillover: how climate warming impacts mosquito-borne viruses." Current Opinion in Virology 72 (2025): 101473. https://doi.org/10.1016/j.coviro.2025.101473
EEA. 2022. Climate Change as a Threat to Health and Well-Being in Europe: Focus on Heat and Infectious Diseases. EEA Report 7/2022. Copenhagen: European Environment Agency. https://www.eea.europa.eu/en/analysis/publications/climate-change-impacts-on-health
Erazo, Diana, Luke Grant, Guillaume Ghisbain, et al. 2024. “Contribution of Climate Change to the Spatial Expansion of West Nile Virus in Europe.” Nature Communications 15 (1): 1196. https://doi.org/10.1038/s41467-024-45290-3
Farooq, Zia, Joacim Rocklöv, and Jan C. Semenza. 2025. “Northward Expansion of Aedes Albopictus-Associated Arbovirus Transmission Risk in Europe.” The Lancet Planetary Health 9 (12): 101378 https://doi.org/10.1016/j.lanplh.2025.101378
Gossner, Céline M., Sofie Dhollander, Lance D. Presser, et al. 2024. “Potential for Emergence of Japanese Encephalitis in the European Union.” Zoonoses and Public Health 71 (3): 274–80. https://doi.org/10.1111/zph.13103
Hiscox, Alexandra, Robert T. Jones, Jessica Dennehy, Will Dyall, Laura Paris, Freya I. Spencer, Fiona Keating et al. "An exploration of current and future vector-borne disease threats and opportunities for change." Frontiers in public health 13 (2025): 1585412. https://doi.org/10.1111/zph.13103
Kerlik, Jana, Ján Hockicko, Mária Avdičová, et al. 2025. “The First Possible Case of Airport Zika Virus Infection in the EU/EEA.” Travel Medicine and Infectious Disease 66 (July): 102864. https://doi.org/10.1016/j.tmaid.2025.102864
Nielsen, Søren Saxmose, Julio Alvarez, Dominique Joseph Bicout, et al. 2020. “Rift Valley Fever – Epidemiological Update and Risk of Introduction into Europe.” EFSA Journal (IT) 18 (3). https://doi.org/10.2903/j.efsa.2020.6041
Van Daalen, Kim R., Cathryn Tonne, Jan C. Semenza, et al. 2024. “The 2024 Europe Report of the Lancet Countdown on Health and Climate Change: Unprecedented Warming Demands Unprecedented Action.” The Lancet Public Health 9 (7): e495–522. https://doi.org/10.1016/S2468-2667(24)00055-0.
Wadman, Meredith. "Mosquito-borne viruses surge in a warming Europe." Science 389, no. 6765 (2025). doi: 10.1126/science.zdp7chd
Willems, Ruben, Nick Verhaeghe, Christian Perronne, Liesbeth Borgermans, and Lieven Annemans. 2023. “Cost of Illness in Patients with Post-Treatment Lyme Disease Syndrome in Belgium.” European Journal of Public Health 33 (4): 668–74. https://doi.org/10.1093/eurpub/ckad045

Vector-borne diseases

Health issues

Observed effects

Projected effects

Tiger mosquito climatic suitability in 2041–2070 under a high-emission scenario

(Click the map to see the interactive version)

Policy responses

References

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Vector-borne diseases

Health issues

Observed effects

Projected effects

Tiger mosquito climatic suitability in 2041–2070 under a high-emission scenario

(Click the map to see the interactive version)

Policy responses

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References

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