CHONGQING, China — For nearly two months, health officials in southern China have been waging war on mosquitos, reviving top-down tactics from the country’s zero-Covid playbook.
Since July, the province of Guangdong alone has reported more than 10,000 cases of chikungunya fever, a mosquito-borne viral disease that mostly circulates in tropical regions. Foshan, a manufacturing hub in densely populated Guangdong, has been the hardest-hit Chinese city — recording over 600 new infections per day at its peak, more than the combined total of 519 cases reported across mainland China from 2010 to 2019.
The unprecedented outbreak prompted Chinese authorities to adopt a containment strategy akin to the country’s strict zero-Covid policy — a “detect and eliminate” approach.
To curb the spread, workers were sent out to spray insecticide in affected areas multiple times a day. The government also required suspected patients to report their cases promptly and comply with the quarantine mandate.
The outbreak in China was triggered by warmer weather this year and a fast-spreading virus strain, Liu Qiyong, chief expert of vector control at China’s Center for Disease Control and Prevention, told state-run broadcaster CCTV.
But the surge in chikungunya cases extends far beyond China as global warming accelerates the spread of infectious diseases, including dengue fever and malaria, a 2025 study found.
As of mid-August, about 270,000 cases of chikungunya had been recorded globally this year, including in the Americas, Europe and Southeast Asia, leading to at least 110 related deaths, according to the Pan American Health Organization.
While no locally acquired cases have been reported in U.S. states or territories since 2019, the Centers for Disease Control and Prevention issued a travel health notice in August urging “enhanced precaution” amid chikungunya outbreaks in China’s Guangdong province and four other countries. The CDC warned that anyone spending time in areas where chikungunya occurs is at risk.
“In this rapidly changing world, infectious disease can disseminate very quickly,” said Jasper Chan, a professor of clinical microbiology and infection at the University of Hong Kong.
“Especially after the recent Covid-19 pandemic, relevant authorities have been quite, I would say, cautious in terms of making these alert issues,” he said.
Chikungunya 101
The chikungunya virus, first identified in Tanzania in 1952, has spread for decades mainly in the Americas, Africa and Asia. It is transmitted primarily through the bites of infected mosquitos and does not spread directly from person to person.
“Chikungunya virus very closely resembles other mosquito-borne viruses like dengue clinically, but they belong to different families,” Chan said.
Its name, which comes from a language in southern Tanzania, means “to bend over,” a reference to the debilitating joint pain it causes. Though it is rarely fatal, chikungunya can have long-lasting, severe symptoms, including muscle pain, headache, nausea, fatigue and rash, according to the World Health Organization.
As there is no specific antiviral drug to cure chikungunya, current treatment is focused primarily on relieving the symptoms. One vaccine is available in the United States. Prevention is the best protection, according to the CDC, which advises people to avoid mosquito bites and get vaccinated if necessary before they travel to places where chikungunya occurs.
Chikungunya has been reported in over 110 countries across every continent except Antarctica, with at least 5.6 billion people living in places at risk from it, the WHO estimated.
The disease spreads through global travelers via mosquitoes. A person gets bitten in one country, boards a plane with the virus still in the bloodstream and lands thousands of miles away, where a mosquito picks up the infection and passes it to the next person. The cycle then begins again, eventually leading to a local outbreak.
Though the United States is unlikely to experience large outbreaks since people in warm areas often stay indoors with air conditioning, experts advise using mosquito repellent, wearing long sleeves and delaying trips to regions with chikungunya outbreaks.
How China battles chikungunya
While chikungunya is not uncommon in other parts of the world, such as Latin America, it is unusual to have big outbreaks in China, where the first imported case was identified in 2008, experts say.
To stop the spread, local authorities have enlisted grassroots workers to disperse insecticide on the streets and clear stagnant pools of water where mosquitos breed. Clinics and hospitals have set up mosquito-proof beds to isolate patients, and residents have been urged to install screen windows and to light mosquito coils at home.
People and organizations in China are bound by law to follow instructions from health officials in containing the virus. Failure to comply can lead to warnings, fines and even civil liability.
Some have criticized the government’s campaign as overkill reminiscent of Covid-era public health controls, while others have praised the quick, large-scale action.
“It’s really great to see years of accumulated old trash removed,” a user wrote on RedNote, a Chinese social media platform similar to Instagram. “But it’s a bit too much to dump out even the cats’ water bowls. That’s a classic case of the one-size-fits-all approach.”
China’s strict controls have curbed the outbreak. As of Aug. 25, Foshan had kept new daily cases under 50 for nine days. Health officials announced that the city of more than 9 million people had ended its public health emergency response, which lasted for about a month.
Experts say the bigger challenge is the impact of climate change, as rising temperatures and more severe weather create new habitats for virus-carrying mosquitos to thrive and spread diseases.
Because of unusually hot weather in recent years, there has been an “increasing number” of locally acquired chikungunya cases in areas that had been unaffected by the virus for the past decade, such as Europe, Chan said.
“Remember, humans are not alone in this globe. We’re living with animals, birds, various other species, as well as all these vectors, including mosquitoes, ticks and other vectors,” he said.
“So we’re just one part of the ecosystem.”
Janis Mackey Frayer reported from Chongqing and Peter Guo from Hong Kong.
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