FEHD releases second batch of gravidtrap indexes for Aedes albopictus in January

     The FEHD has so far released two batches of gravidtrap indexes for Aedes albopictus in January 2026, covering 24 survey areas; most of the areas recorded 0 per cent, indicating that the distribution of Aedes albopictus mosquitoes was not extensive.     Starting in August 2025, following the completion of the surveillance of individual survey areas, and once the latest gravidtrap index and the density index are available, the FEHD has been disseminating relevant information through press releases, its website and social media. It aims to allow members of the public to quickly grasp the mosquito infestation situation and strengthen mosquito control efforts, thereby reducing the risk of chikungunya fever (CF) transmission.

     Following recommendations from the World Health Organization and taking into account the local situation in Hong Kong, the FEHD sets up gravidtraps in districts where mosquito-borne diseases have been recorded in the past, as well as in densely populated places such as housing estates, hospitals and schools to monitor the breeding and distribution of Aedes albopictus mosquitoes, which can transmit CF and dengue fever (DF). After reviewing the present DF and CF vector surveillance programme, the FEHD has expanded the coverage for monitoring Aedes albopictus mosquitoes starting from 2026. The number of survey areas set up in the community has been revised to 62, with some survey areas renamed. Additional gravidtraps will also be set up at different locations across the territory to strengthen the monitoring of the breeding of mosquitoes. Under the present surveillance mechanism, the FEHD has set up gravidtraps in survey areas of the community, with a surveillance period of two weeks. During the surveillance period, the FEHD will collect the gravidtraps once a week. After the first week of surveillance, the FEHD will immediately examine the glue boards inside the retrieved gravidtraps for the presence of adult Aedine mosquitoes to compile the Gravidtrap Index (First Phase) and Density Index (First Phase). At the end of the second week of surveillance, the FEHD will instantly check the glue boards for the presence of adult Aedine mosquitoes. Data from the two weeks of surveillance will be combined to obtain the Area Gravidtrap Index and the Area Density Index. The gravidtrap and density indexes for Aedes albopictus in different survey areas, as well as information on mosquito prevention and control measures, are available on the department’s webpage (www.fehd.gov.hk/english/pestcontrol/dengue_fever/Dengue_Fever_Gravidtrap_Index_Update.html#Issued at HKT 17:00