Understanding the Growing Risk of Chikungunya
A recent study has revealed that warmer temperatures could significantly expand the habitats of mosquitoes, leading to an increased risk of chikungunya in various parts of the world. This mosquito-borne viral disease is now considered a global health concern, with 139 countries or regions identified as high-risk areas. These regions account for 21.3% of the Earth’s land mass.
Dr Ye Xu, a co-author of the study, emphasized that under climate change models, the virus is expected to spread further north into temperate regions. Areas such as northeastern North America, central Europe, and East Asia are particularly at risk. The research was conducted by scientists in China and published in the journal Frontiers in Cellular and Infection Microbiology.
How Climate Change Affects Mosquito Behavior
Chikungunya is primarily transmitted by the yellow fever mosquito, Aedes aegypti, which thrives in human settlements in tropical regions. However, changes in global climate and increased population mobility have contributed to the spread of disease-carrying mosquitoes and new viral variants.
During a significant outbreak in the Indian Ocean between 2005 and 2006, scientists observed a mutation in the virus that allowed it to adapt to a different mosquito species: the Asian tiger mosquito. Dr Yang Wu, another co-author of the study, explained that this mosquito can tolerate cooler conditions better than the yellow fever mosquito. As a result, warming temperatures may enable the Asian tiger mosquito to establish itself in previously too cold regions.
When these mosquitoes become established in new areas, the likelihood of local chikungunya transmission increases. Additionally, warmer temperatures accelerate the development of the virus within the mosquito. At temperatures ranging from 18°C to 28°C, the virus becomes ready to spread up to four to five times faster, increasing the risk of outbreaks.
The Global Spread of Chikungunya
The researchers warned that chikungunya has become a major global health threat. Indigenous transmission has been reported in 114 countries, putting more than three-quarters of the world’s population at risk. Although the case fatality rate is relatively low—approximately 1.3 per thousand—it results in a significant loss of healthy life years annually, estimated at around 284,000 disability-adjusted life years.
To understand how the disease might spread in the future, the researchers modelled the requirements of the chikungunya virus and its two primary mosquito vectors. They used tens of thousands of geo-tagged records of mosquito presence worldwide. Based on 16 climate scenarios developed by the United Nations’ Intergovernmental Panel on Climate Change (IPCC), they projected how these ranges might change by 2100.
While the exact expansion of the disease depends on the chosen climate scenario, certain regions consistently emerged as potential hotspots. These include north-central Europe, northeastern North America, and eastern Asia. Currently, the virus is not endemic to Europe or North America, and cases in these regions are typically linked to travelers from tropical or subtropical areas.
Preparing for Future Outbreaks
The geographic extent and outbreak potential of chikungunya are fundamentally determined by its transmission vectors—the mosquitoes that carry the virus. As the climate continues to change, the distribution of these vectors will also shift, increasing the risk of disease in new areas.
In 2025, there were 502,264 reported chikungunya cases globally, with 186 deaths recorded across 41 countries and territories, according to the Pan American Health Organization. Researchers warn that this disease burden is likely to increase under climate change, which is already altering the distribution patterns of infectious diseases.
Dr Xu urged caution, stating that while the public does not need to panic, health systems should prepare early. Among the proposed measures, tracking mosquitoes, training healthcare workers to quickly recognize the virus, strengthening mosquito control efforts, and setting up rapid-response plans before outbreaks occur are essential steps.
These actions are especially important in temperate regions where chikungunya has not traditionally been a public health concern. Countries along the identified risk zones, including the United Kingdom, Germany, the United States, China, and Japan, must prioritize pre-emptive vector surveillance and clinical diagnosis training before 2040, the authors concluded.
