Mosquitoes Are Spreading Across Europe, Increasing Disease Risks 

A blood-engorged female mosquito of Aedes albopictus (the Asian tiger mosquito) feeding on a human host. Content Providers(s): CDC

Mosquitos are spreading across Europe, increasing the risk of various diseases. This September, Romania is facing growing concern over mosquito-borne diseases. One of them is the West Nile virus, circulating in the region due to warmer conditions, which create opportunities for mosquito populations to remain active for longer.

Romania has an established population of Aedes albopictus (the Asian tiger mosquito), which can transmit dengue (a viral infection) and chikungunya (a virus). At the same time, in London, an Aedes aegypti mosquito, capable of transmitting dengue, chikungunya and Zika(virus infection), was found breeding in homes in east London for the first recorded time. This highlights how warmer conditions can create opportunities for tropical mosquito species to survive farther north.

The concern is not simply that there are more mosquitoes, but also that longer warm seasons give mosquitoes more time to survive, reproduce and spread diseases.

Higher temperatures can also speed up the development of viruses inside mosquitoes. Romania’s epidemiologists are therefore calling for better preparedness for diseases usually linked to warmer parts of Europe and the tropics. Also, the Aedes aegypti mosquito discovery in the UK shows that mosquito species are expanding into new areas across Europe.

What Is Happening: Mosquitoes and Disease Risk in Europe

• The West Nile virus is already a recurring health risk in Romania: By 26 August 2026, Romania had reported 45 locally acquired West Nile cases across 15 affected areas.
• The Asian tiger mosquito is already populating Romania: Aedes albopictus (Asian tiger mosquito) is established in 10 of Romania’s 42 monitored administrative units. This creates the conditions needed for possible local transmission of dengue and chikungunya.
• Dengue and chikungunya are no longer only southern European concerns: Locally acquired dengue cases have also been reported in Europe. France and Italy recorded substantial locally acquired chikungunya outbreaks in 2025.
• A tropical mosquito has now bred in London: Aedes aegypti (yellow fever mosquito), normally associated with tropical and subtropical regions, was found breeding inside homes in east London in September 2026. This is the first recorded breeding event of the species in the UK, although authorities say it is not currently established there, and the public-health risk remains low.
• Mosquitoes are moving into new areas: European Centre for Disease Prevention and Control (ECDC) reports that Aedes albopictus, commonly known as the (Asian tiger mosquito), has continued to expand northwards and westwards in Europe. Additionally, Aedes aegypti (yellow fever mosquito), has also established populations in parts of Europe.

Why This is Getting Worse 

Warmer temperatures and longer summers are changing the conditions mosquitoes depend on.

Higher temperatures can allow mosquitoes to survive for longer, reproduce more successfully and expand into areas that were previously too cold. Temperature also affects how quickly viruses develop inside mosquitoes, potentially shortening the time between a mosquito becoming infected and becoming capable of transmitting the virus.

Rapid Arctic warming may also influence summer weather farther south. As the Arctic warms faster than the rest of the Northern Hemisphere, the temperature difference between the Arctic and mid-latitudes becomes smaller. This can weaken the jet stream, meaning the high-altitude winds that help steer weather systems. This can contribute to longer periods of warm and dry weather in Europe, creating more favourable conditions for mosquitoes to survive, breed, and expand into new areas.

However, climate change is not the only driver. International travel can introduce infected people and mosquitoes. Additionally, trade and the movement of goods can transport mosquito eggs and larvae. Standing water then provides breeding sites. Together, these factors can help mosquitoes establish in places where warmer temperatures have made survival easier.

Disease Risk From Mosquitoes: What This Means for People 

• West Nile virus: Most infections are mild or asymptomatic, but severe disease can cause encephalitis, meningitis and other neurological complications, in older or vulnerable people.
• Dengue: Local transmission could cause high fever, severe headache, muscle and joint pain and, in some cases, severe disease involving bleeding or organ complications.
• Chikungunya: Infection commonly causes fever and severe joint pain, which can persist for months or longer in some people.
• Zika: Aedes aegypti and Aedes albopictus can transmit Zika; infection is often mild, but the virus can cause serious complications during pregnancy.
• Longer exposure season: Warmer conditions can extend the period during which people are exposed to mosquitoes, creating more opportunities for transmission.

The Urgent Response Needed

What needs to change:

• Strengthen mosquito surveillance: Track where Aedes and Culex mosquitoes are found and when they are most active (location, numbers, season).
• Build early-warning systems: Combine temperature, rainfall, mosquito numbers and disease cases to identify areas at increasing risk.
• Monitor travel-related infections: Strengthen monitoring of travellers returning from areas with dengue, chikungunya or Zika.
• Control breeding sites: Focus on removing standing water and treating mosquito larvae (buckets, flowerpots), rather than relying only on spraying, which has temporary effects and may increase resistance.
• Prepare healthcare systems: Train healthcare workers to recognise unfamiliar mosquito-borne diseases and improve rapid testing and diagnosis.

What YOU Can Do:

• Remove standing water such as flowerpots, buckets, and make sure to regularly clean pools.
• Protect yourself by adopting one of the following preventions: window screens, mosquito nets, repellent, long clothing.
• Seek medical advice if you develop fever, severe headache, muscle/joint pain or rash after mosquito exposure, or after travel to affected areas.
• Follow local health warnings and mosquito surveillance updates.

Read more: Extreme weather events | Health risks | Climate Risks Daily

Original source: Invasive tropical mosquito found breeding in east London | Invasive species | The Guardian, https://adevarul.ro/stiri-interne/sanatate/tantarii-devin-o-problema-epidemiolog-romania-2553701.html