Hong Kong Launches New Mosquito Control Trial After First Dengue Case Since 2024

Hong Kong has announced a new trial to combat dengue fever by infecting male mosquitoes with bacteria to prevent their offspring from reaching maturity, following the city’s first locally recorded case of the disease in over a year.

The initiative, described as a “mosquito-to-control-mosquito” strategy, will involve releasing male mosquitoes infected with a designated bacterium. According to Donald Ng Man-kit, Director of Food and Environmental Hygiene, any offspring produced after mating between these infected males and wild females will fail to reach maturity, thereby reducing the overall mosquito population over time.

The decision comes after a 21-year-old man developed dengue fever symptoms last week and tested positive for the virus. Health officials confirmed he had not travelled outside Hong Kong recently and was bitten by mosquitoes near a road construction site in Penny’s Bay on Lantau Island, where he works.

Environmental inspections at the site revealed multiple areas conducive to mosquito breeding, including drainage channels with weeds and leaves, as well as stagnant water. In response, personnel from the Centre for Health Protection (CHP) and the Food and Environmental Hygiene Department (FEHD) have conducted mosquito control and preventive measures at the location and surrounding areas.

Albert Au, head of the Centre for Health Protection, described the current dengue fever risk in Hong Kong as “moderate,” citing rising temperatures and the imminent rainy season as factors that increase mosquito breeding opportunities. He noted that infection rates for mosquito-borne diseases remain high in Southeast Asia and neighbouring regions, meaning the risk of an outbreak cannot be neglected.

So far this year, Hong Kong has recorded 12 imported cases of dengue fever, all involving individuals who had travelled abroad. The recent local case marks the first instance of domestic transmission since 2024, when five local cases were reported alongside 156 imported infections, bringing the total to 161 cases for that year.

The World Health Organization has reported a significant global increase in dengue fever incidence over the past two decades, with over 14 million cases recorded in 2024 alone — a record number. From January to July 2025, more than four million cases and over 3,000 dengue-related deaths were reported across 97 countries and territories.

Neighbouring tourist destinations such as Indonesia, India, and Vietnam have each reported over 100,000 dengue cases so far in 2025, while Malaysia and Thailand have each exceeded 40,000 cases. Singapore has also recorded more than 3,500 cases during the same period.

Health officials continue to advise the public to prevent mosquito bites by wearing loose, light-coloured, long-sleeved clothing and using insect repellent containing DEET on exposed skin or clothing, particularly when visiting areas affected by mosquito-borne diseases.