A New Frontier for a Tropical Disease: Chikungunya Set to Reach Cooler Climates by 2100
A new body of scientific research indicates that the chikungunya virus, a mosquito-borne disease historically confined to tropical and subtropical regions, is projected to expand into temperate areas of North America, Europe, and East Asia by the year 2100. Two separate studies published in 2025 identify climate change and the spread of the Asian tiger mosquito (Aedes albopictus) as primary drivers for this potential geographic shift.
About Chikungunya
Chikungunya is a viral disease transmitted by Aedes mosquitoes. Symptoms include high fever, severe joint pain, muscle pain, headache, fatigue, nausea, and rash. The disease can be debilitating and, in rare cases, fatal, particularly in young children and older adults. It is classified as a neglected tropical disease by the World Health Organization (WHO).
Projected Expansion and High-Risk Regions
A study published in Frontiers in Cellular and Infection Microbiology modeled the future niche of the virus and its vectors under 16 climate scenarios from the Intergovernmental Panel on Climate Change (IPCC). The research, led by scientists at Zhejiang Chinese Medical University and the Guangzhou Customs Technology Center, consistently identified three regions as future high-risk zones across all models:
- North-central Europe
- Northeastern North America
- Eastern Asia
The study projects that these regions should prepare mosquito monitoring and public health measures by 2040.
Lowered Temperature Thresholds and Extended Transmission Seasons
A second study, published in the Journal of the Royal Society Interface by researchers at the UK Centre for Ecology and Hydrology (UKCEH), determined that the minimum temperature required for the chikungunya virus to incubate within the Asian tiger mosquito is between 13°C and 14°C. This is 2.5°C to 4°C lower than previous estimates of 16°C-18°C. The study utilized data from 49 previous studies to calculate viral incubation times across various temperatures.
This revised threshold produces significantly longer annual transmission windows:
- Southern Europe (Spain, Portugal, Italy, Greece): Over six months per year.
- Central Europe (Belgium, France, Germany, Switzerland): Three to five months per year.
- Southeast England: Up to two months per year.
Role of the Mosquito Vector
Both studies identify the Asian tiger mosquito (Aedes albopictus) as the primary driver of the virus’s potential expansion. According to the Frontiers study, this species explains over 70% of the predicted virus distribution because it tolerates cooler conditions better than the yellow fever mosquito (Aedes aegypti). The UKCEH study notes that the Asian tiger mosquito is an invasive species currently moving northward across Europe as temperatures rise. It has been detected, but not yet established, in the UK.
Current Epidemiology and Recent Outbreaks
According to the European Centre for Disease Prevention and Control (ECDC), as of 2026, approximately 33,000 symptomatic cases and nine deaths were reported globally, predominantly in South America. The virus is not currently endemic to Europe or North America.
Small numbers of locally acquired cases have been reported in over ten European countries in recent years. Notably, large outbreaks of hundreds of cases occurred in France and Italy in 2025. France recorded over 800 locally acquired cases in 2025, compared to approximately 30 cases over the preceding decade. These cases were introduced by travelers from tropical French overseas territories.
In the UK, no local transmissions have been reported. However, 73 cases among individuals who contracted the virus abroad were recorded between January and June 2025—nearly three times higher than the same period in 2024.
Mechanism of Transmission and Outbreak Dynamics
An outbreak typically begins when an infected traveler from a tropical region is bitten by a local Asian tiger mosquito. The virus then incubates inside the mosquito. If the incubation period is shorter than the mosquito's lifespan, the virus will be present in the mosquito's saliva, enabling it to infect the next person it bites.
Historically, cold winters in Europe halted tiger mosquito activity, acting as a natural break on transmission. Scientists are now observing year-round tiger mosquito activity in southern Europe.
Expert Statements and Recommendations
Dr. Ye Xu (Zhejiang Chinese Medical University) stated that public health officials can prepare by tracking Aedes mosquitoes, training doctors, strengthening mosquito control, and setting up rapid-response plans.
Dr. Yang Wu (Guangzhou Customs Technology Center) noted that warming may allow the Asian tiger mosquito to establish in previously cold areas, increasing local transmission risk.
"Europe's rate of warming is approximately double the global average, making the lower temperature limit for virus spread significant," said Sandeep Tegar (UKCEH). "Identifying specific locations and the months of possible transmission will enable local authorities to decide when and where to take action."
Dr. Steven White (UKCEH) stated that the presence of chikungunya in Europe was once considered unlikely. Regarding the potential for larger outbreaks, White anticipated "much bigger outbreaks because you don’t have this natural firebreak."
Dr. Diana Rojas Alvarez (World Health Organization) stated the study indicates transmission in Europe might become more evident over time. She noted that up to 40% of individuals experience arthritis or severe pain five years after infection. She emphasized that Europe can still control mosquito spread through community education on removing stagnant water, wearing protective clothing, using repellent, and implementing surveillance systems.