Chikungunya Virus Now a Major Threat Across Europe as Climate Change Accelerates Spread
A groundbreaking study has uncovered that chikungunya, an excruciatingly painful tropical disease, can now be transmitted by mosquitoes across the majority of Europe. This alarming development is directly linked to the climate crisis and the northward expansion of invasive mosquito species, with hundreds of cases already reported in France and Italy during 2025.
Climate Crisis Lowers Temperature Threshold for Virus Transmission
The research, published in the Journal of Royal Society Interface, represents the first comprehensive analysis of how temperature affects the incubation period of the chikungunya virus within the Asian tiger mosquito. Scientists discovered that the minimum temperature required for transmission is now 2.5 degrees Celsius lower than previous estimates, standing at just 13-14 degrees Celsius.
"This new temperature threshold is quite shocking," stated Sandeep Tegar, lead author from the UK Centre for Ecology and Hydrology. "The rate of global warming in Europe is approximately double the global average, meaning the northward expansion of this disease is just a matter of time."
Expanding Geographic Reach and Transmission Windows
The revised temperature parameters mean chikungunya infections are now possible for more than six months annually in southern European nations including Spain, Portugal, Italy, and Greece. Even in countries like Belgium, France, Germany, and Switzerland, transmission windows extend to three to five months each year.
In southeast England, the virus could potentially spread for up to two months annually. While the Asian tiger mosquito has been detected in the United Kingdom, it has not yet established permanent populations. However, record numbers of imported cases—73 between January and June 2025, nearly triple the previous year's count—highlight the growing risk.
From Tropical Confinement to European Outbreaks
First identified in Tanzania in 1952, chikungunya was historically confined to tropical regions where millions of infections occur annually. The disease causes severe, prolonged joint pain that can be debilitating and occasionally fatal, particularly among young children and older adults.
Dr. Steven White of UKCEH emphasized the dramatic shift: "Twenty years ago, suggesting chikungunya and dengue would become European diseases would have seemed madness. Now everything has changed due to invasive mosquitoes and climate change."
The scale of recent outbreaks underscores this transformation. France, which recorded only about 30 cases over a decade, experienced over 800 infections in 2025 alone, primarily originating from travelers returning from French tropical territories experiencing outbreaks.
Year-Round Transmission and Lost Firebreaks
Traditionally, Europe's cold winters provided a natural firebreak by halting mosquito activity and interrupting disease transmission cycles between years. However, scientists are now observing year-round tiger mosquito activity in southern Europe, potentially allowing outbreaks to amplify as continental temperatures continue rising.
"Our intuition suggests we will see much larger outbreaks because this natural firebreak is disappearing," warned Dr. White. The UKCEH team is actively investigating this concerning trend.
Public Health Implications and Protective Measures
Dr. Diana Rojas Alvarez, who leads the World Health Organization's team on vector-borne viruses, noted that chikungunya can have devastating long-term effects, with up to 40% of patients still experiencing arthritis or severe pain five years after infection.
"Climate has a huge impact, but Europe still has opportunities to control mosquito spread," she emphasized. Key protective strategies include:
- Community education about eliminating standing water where mosquitoes breed
- Wearing long, light-colored clothing and using effective repellents
- Establishing robust surveillance systems by health authorities
- Preventing the establishment of invasive mosquito species in new regions
While vaccines for chikungunya exist, they remain costly, making bite prevention the most accessible protection method. The Asian tiger mosquito, which bites during daylight hours, continues its northward expansion across Europe as temperatures rise, carrying not only chikungunya but also dengue and Zika viruses.
This study provides crucial detailed information about specific locations and months of potential transmission, enabling local authorities to implement targeted interventions at the most critical times. As global heating continues unabated, European nations must prepare for a future where tropical diseases become increasingly commonplace across the continent.
