China’s health authorities have reported a major surge in patients suffering from chikungunya fever, a mosquito-borne viral disease, in the southern Guangdong province.

Between July 27 and Aug. 2, 2,892 cases of the disease were reported, with 96% concentrated in the province’s manufacturing hub of Foshan, according to an update on the situation from the provincial center for disease control and prevention on Sunday. No severe or fatal cases have been recorded.

The outbreak traces back to July 8, when authorities identified the country’s first local chikungunya fever transmission of the year — believed to stem from an imported infection — in Lecong Town, in Foshan’s Shunde District. Cumulative cases in Guangdong surpassed 7,700 as of Saturday, while seven cases have been reported in Macau and one in Hong Kong.

Chikungunya fever is primarily transmitted through bites from Aedes mosquitoes carrying the chikungunya virus. The disease can also be transmitted from mother to baby in utero and, in rare cases, via blood transfusion or contact with infected blood. The general population is susceptible to the chikungunya virus, and infection can lead to long-term immunity.

Health experts say that the rapid spread of the epidemic in Guangdong has been initially contained, with a decline in newly reported cases, particularly in Shunde District.

Due to the global prevalence of chikungunya fever and Guangdong province’s outsized role in China’s international trade, the risk of imported cases remains. The surge in mosquito populations during typhoon season and heavy rainfall — which creates ideal breeding grounds — has further complicated epidemic prevention and control.

Key prevention measures include eliminating areas of stagnant water and mosquito breeding sites to reduce mosquito density, along with personal use of mosquito repellents, nets, and other methods to prevent bites. And travelers to chikungunya fever-endemic areas are advised to take relevant precautions.

Patients typically develop symptoms one to 12 days after exposure to the virus, most commonly presenting with fever, joint pain, and a rash. While symptoms usually resolve within a week, joint pain may persist for months. Globally, approximately one million people contract the disease each year, with a fatality rate of up to 0.1%.

On July 25, cases of chikungunya fever reported in Guangzhou, Guangdong’s capital, prompted a weeklong citywide mosquito prevention and control campaign from July 26 to Aug. 1.

On July 30, a team from Guangzhou’s Sun Yat-sen University released larvae of Toxorhynchites splendens mosquitoes, which prey on Aedes aegypti mosquito larvae, in the city’s Sanshui District to control the spread of the disease. This mosquito species can consume 80 to 100 Aedes larvae over its lifetime and does not feed on blood, posing no threat to humans or animals.

China first detected imported chikungunya cases in 2008. Subsequent localized outbreaks linked to imported cases occurred in 2010 and 2019, though they remained limited in scale.

Guangdong’s current rapid and widespread chikungunya transmission marks a significant shift from previous sporadic cases. Experts attribute the ferocity of this outbreak to multiple factors, including high global transmission rates — the virus is believed to be present in 119 countries and regions, according to the World Health Organization’s July 22 alert, warning nations to prepare for potential large-scale outbreaks.

Liu Qiyong, chief expert at the Chinese Center for Disease Control and Prevention, told state broadcaster CCTV that favorable climatic conditions for mosquito breeding, combined with the introduction of a highly transmissible strain from the Indian Ocean, have contributed to this year’s outbreak.

On July 31, the National Health Commission of China and the State Administration of Traditional Chinese Medicine jointly released the 2025 clinical guidelines for chikungunya fever management. The guidelines emphasize symptomatic and supportive care as the primary treatment approach, given the current absence of specific antiviral therapy. They explicitly advise against antibiotic misuse, corticosteroids, and immunoglobulin therapy to combat the disease.

Editor: Tom Arnstein.

(Header image: VCG)