Mosquito-Borne Chikungunya Virus Cases Rise Due to Travelers and Climate Change

This summer 2025 saw a huge uptick in chikungunya virus cases — a mosquito-borne illness — in China's Guangdong Province. Since then, cases have shifted from Southern China to other areas of the globe, including France and Italy.

A report in the journal Biocontaminant looks at how a combination of travel and climate change has led to outbreaks outside of the province.

"The outbreak reflects both the global spread of chikungunya and the favorable conditions for mosquito-borne diseases in southern China," said lead author Guang-Guo Ying of South China Normal University in a press statement.

Although the virus isn’t highly contagious and cannot spread from person to person, there are steps people can take to lower their risk of infection and help stop the spread of this virus.

How the Chikungunya Virus Spreads

The chikungunya virus is transmitted through the bites of infected Aedes albopictus or Aedes aegypti mosquitoes, which can be found in tropical and subtropical regions around the globe. The virus then remains in the bloodstream and can be transmitted back to uninfected mosquitoes when they bite a human carrying the chikungunya virus.

In very rare cases, some individuals have become infected with the virus after experiencing blood-to-blood contact in a laboratory or medical setting.

According to the Centers for Disease Control and Prevention (CDC), over 100 countries have reported outbreaks of the chikungunya virus, with travel being one of the primary spreaders.

How Traveling Leads to Chikungunya Virus Spread

According to the Cleveland Clinic, patients bitten by an infected mosquito can start experiencing chikungunya symptoms within five to seven days. These symptoms typically include fever and joint pain. By this time, an infected person can be bitten by an uninfected mosquito and transmit the virus to it.

This infection and reinfection cycle is likely how these smaller outbreaks are spreading in Europe and other parts of the world, outside of Southern China.

According to the European Centre for Disease Prevention and Control, as of October 5, 2025, both France and Italy have reported a surge in chikungunya cases, with France reporting 700 cases and Italy reporting 353.

It’s possible that travelers from these regions ventured to infected regions and brought the virus back with them, spreading it to the local mosquitoes.

According to the European Climate and Health Observatory, over 90 percent of the chikungunya virus cases are related to travel. According to the same source, after a mosquito bites an infected person, it can transmit the virus to an uninfected person in less than a week.

Climate Change’s Impact and Slowing the Spread

As global temperatures continue to rise, so too could populations of A. albopictus or A. aegypti. These mosquitoes lay their eggs in still or standing water and have adapted well to urbanized environments, according to the press statement.

“Climate change can increase the likelihood of extreme weather phenomena, including heavy rainfall and prolonged droughts. This phenomenon has been linked to the spread of arboviruses in endemic regions and is now observed in previously unaffected areas, indicating a broader environmental impact,” the study authors wrote in their report.

Ways to mitigate these mosquito populations include trying to remove standing water sources or covering them after periods of heavy rainfall.

According to the CDC, there are also two chikungunya vaccines, and having them administered before traveling to regions with known infections can help reduce the spread.

This article is not offering medical advice and should be used for informational purposes only.

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