What is chikungunya fever and how to stay safe?

As of July 24, Foshan City in south China's Guangdong Province has reported more than 4,000 confirmed cases of chikungunya fever. While China first recorded imported cases as early as 2008 and saw limited local outbreaks in 2010 and 2019, the current outbreak marks the largest surge to date.

Why is this outbreak more severe, and how can the public protect themselves? CMG speaks with Liu Qiyong, chief expert in Vector-Borne Disease Control of the Chinese Center for Disease Control and Prevention (CDC), who is leading chikungunya fever prevention efforts in Foshan.

Why is Foshan's chikungunya outbreak more severe than ever?

Multiple contributing factors, with intensified global transmission as the primary driver, are behind this outbreak, Liu says. As of July 22, the WHO has reported active chikungunya outbreaks across 119 countries and territories, urging nations to bolster preparedness against potential epidemics.

"With the virus spreading globally, imported cases have inevitably reached China," Liu explains. "Given the established presence of local transmission vectors, particularly Aedes mosquitoes, these imported infections have fueled sustained local transmission cycles, leading to concentrated, small-scale outbreaks in affected regions."

In addition to global spread, climatic conditions and the unique characteristics of the viral strain have further amplified the outbreak's scale in Foshan City this year, making it notably more severe than past incidents.

Does it cause joint pain? How long does this symptom last? 

When infected mosquitoes bite humans, transmission occurs. The virus then begins replicating rapidly in the body. Once the viral load reaches a critical threshold and spreads into the circulatory system, the body's organs respond.

"Within approximately one to two days, typical symptoms emerge, including fever, skin rashes, and joint pain," Liu noted.

The name "chikungunya" originates from Tanzania, meaning "to bend over," a vivid descriptor of its hallmark clinical feature: the characteristic stooped posture caused by severe arthralgia, or joint pain, which also serves as a key diagnostic differentiator.

Clinical data indicate 20 to 30 percent of infected individuals develop polyarthralgia, pain in multiple joints. While most cases resolve within weeks to months. Only a certain proportion of patients (in the single-digit percentage range) experience symptoms persisting beyond six months to a year or longer. In some cases, this can even lead to chronic sequelae, such as reduced work capacity and persistent joint mobility impairment.

Are mosquitoes more active in spreading viruses at higher temperatures?

The activity of mosquitoes is closely tied to temperature, but this relationship follows an optimal range rather than a simple linear trend. These vectors thrive at temperatures between 25 and 28 degrees Celsius, but exposure to extreme heat can paradoxically suppress their populations.

While Aedes mosquitoes are known as daytime biters, their feeding activity follows a distinct bimodal rhythm, peaking during early morning (7-9 a.m.) and late afternoon (5-7 p.m.) hours.

"Accordingly, mosquito control operations in Foshan now precisely time insecticide spraying to coincide with these peak activity periods," Liu said.

Do areas without confirmed cases need to strengthen preventive measures?

Liu noted that regions without active outbreaks need not overreact, and routine preventive measures are adequate. However, in areas with confirmed transmission, intensified mosquito control and personal protection are essential.

Special attention should be given to areas near reported cases, where systematic mosquito eradication, prevention protocols and community-driven anti-mosquito initiatives must be prioritized.

Choose the right repellents

To effectively prevent mosquito-borne diseases like chikungunya, proper selection and use of repellents are essential.

Liu advises consumers to verify that a repellent carries both a registered pesticide number and a valid production license, ensuring efficacy and safety. Users should adhere to the product's stated protection period, though applying more frequently may improve effectiveness.

"Additionally, wearing light-colored, long-sleeved clothing outdoors can further minimize exposure to mosquitoes," Liu added.

Together, these measures significantly reduce the risk of Aedes mosquito bites, the primary vector of chikungunya.

Mosquito control is the key

There is currently no vaccine or specific treatment for chikungunya fever, making mosquito control essential for prevention. Key measures include eliminating adult mosquitoes, removing stagnant water and avoiding bites.

Newborns, adults over 65 and individuals with chronic health conditions face a higher risk of severe infection and complications. These groups should seek medical care immediately if symptoms appear.

Due to the global increase in cases this year, travelers visiting outbreak regions – such as Foshan, Southeast Asia, Africa or South America – should check local health advisories and take strict anti-mosquito precautions before departure.

"Upon return, monitor your health for 14 days. Seek prompt medical attention if you develop fever, rash or joint pain, and disclose your travel history and any mosquito exposure for accurate diagnosis and treatment," Liu advised.