Understanding the Growing Risk of Chikungunya
A recent study has revealed that rising global temperatures could significantly expand the habitats of mosquitoes, leading to an increased risk of chikungunya in many parts of the world. The research, conducted by scientists in China and published in the journal Frontiers in Cellular and Infection Microbiology, highlights that 139 countries or regions are currently at risk for this mosquito-borne viral disease. This accounts for approximately 21.3% of the world’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 northward into temperate regions, particularly in northeastern North America, central Europe, and East Asia. This shift underscores the urgent need for global health systems to adapt to the evolving threat posed by chikungunya.
How Climate Change Influences Mosquito Behavior
Chikungunya is primarily transmitted by the yellow fever mosquito, Aedes aegypti, which thrives in human settlements within tropical regions. However, recent changes in climate and increased population mobility have contributed to the expansion of disease-carrying mosquitoes and the spread of 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, making it more likely to establish itself in areas that were previously too cold.
“When suitable mosquitoes become established, the chance of local chikungunya transmission increases,” said Dr Wu. Additionally, warmer temperatures accelerate the development of the virus inside the mosquito. At temperatures between 18°C and 28°C, the virus becomes ready to spread up to four to five times faster, significantly 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. The case fatality rate is approximately 1.3 per thousand, resulting in about 284,000 disability-adjusted life years lost annually due to illness or disability.
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 using tens of thousands of geo-tagged records of their presence worldwide. They projected how these ranges might change by 2100 based on 16 climate scenarios developed by the United Nations’ Intergovernmental Panel on Climate Change (IPCC).
While the exact extent of the disease’s spread depends on the chosen climate scenario, certain regions—such as north-central Europe, northeastern North America, and eastern Asia—are consistently identified as potential hotspots.
Preparing for Future Outbreaks
Although chikungunya is not currently endemic to Europe or North America, cases in these regions are typically linked to travelers from tropical or subtropical areas. The researchers found that the geographic spread and outbreak potential of chikungunya are largely determined by the mosquitoes that carry the virus.
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. The researchers noted that this disease burden is expected to rise under climate change, which is reshaping the distribution of infectious diseases.
Dr Xu urged public health authorities to prepare early rather than panic. Among the proposed measures, tracking mosquito populations, training healthcare workers to identify the virus quickly, strengthening mosquito control efforts, and establishing rapid-response plans before outbreaks occur are critical steps.
“These steps are especially important in temperate regions where the disease has not been a routine public-health concern,” added Dr Xu. Countries such as the United Kingdom, Germany, the United States, China, and Japan must prioritise pre-emptive vector surveillance and clinical diagnosis training before 2040 to mitigate the growing threat of chikungunya.
