On Aug. 8, 2025, experts in mosquito-borne infectious diseases are warning against excessive insect eradication campaigns as cities in southern China seek to eliminate mosquitoes in the fight against chikungunya fever.

Guangdong province in southern China has been hit by a wave of chikungunya fever cases, with more than 7,000 people affected so far – marking the most severe outbreak since the disease was first detected in China nearly two decades ago.

Chikungunya fever is a viral disease transmitted by the Aedes mosquito. While rarely fatal, it can lead to symptoms such as fever, rash and joint pain. The combination of heat, humidity and rain has created a favourable environment for mosquitoes to thrive and spread the disease.

However, Jin Dongyan, a professor of biomedical science at the University of Hong Kong, said the efforts to kill all kinds of mosquitoes in the cities, including those in homes and shops, may be missing the target because most of them did not carry the virus.

To more effectively curb the chikungunya outbreak, authorities should examine patients and identify areas where the virus-carrying mosquitoes were present, Jin suggested. Routine mosquito monitoring was also important, he said, citing Hong Kong’s experience as an example.

To understand the distribution of the Aedes mosquito, the Hong Kong authorities have placed traps in various locations across the city to monitor their breeding. When the density of these mosquitoes reaches a certain level, corresponding measures are triggered.

Although mainland China has reported several instances of imported chikungunya fever leading to sporadic local cases, these outbreaks have not resulted in a pandemic in the past. According to the Guangdong disease control centre, a total of 4,824 cases had been reported in the province by July 26. The province reported 2,892 new cases a week later, 2,770 of which were in Foshan and 65 in Guangzhou.