The Food and Environmental Hygiene Department (FEHD) today (September 11) released the first batch of gravidtrap indexes and density indexes for Aedes albopictus in September, covering 20 survey areas, as follows:
 

District	Survey Area	September 2025
		First Phase Gravidtrap Index	First Phase Density Index
Eastern	Chai Wan West	0.0%	N/A
	Shau Kei Wan and Sai Wan Ho	9.8%	1.6
Southern	Aberdeen and Ap Lei Chau	1.8%	1.0
Islands	Tung Chung	5.9%	1.0
Sham Shui Po	Lai Chi Kok	0.0%	N/A
Kowloon City	Ho Man Tin	5.8%	1.0
	Hung Hom	9.4%	1.4
	Lok Fu West	5.2%	1.0
Kwun Tong	Kwun Tong Central	0.0%	N/A
Sai Kung	Sai Kung Town	5.7%	1.0
	Ngau Liu and Muk Min Shan	4.3%	1.0
Sha Tin	Sha Tin Town Centre and Fo Tan	0.0%	N/A
North	Fanling	3.8%	1.0
Yuen Long	Yuen Kong	0.0%	N/A
	Ki Lun Shan	0.0%	N/A
	Sung Shan	0.0%	N/A
Tuen Mun	Tuen Mun South	0.0%	N/A
Tsuen Wan	Tsuen Wan Town	3.5%	1.0
	Tsuen Wan West	0.0%	N/A
Kwai Tsing	Lai King	3.8%	1.5

     Among the first batch of First Phase Gravidtrap Indexes covering 20 survey areas in September, all were below 10 per cent.

     Among these 20 survey areas, 13 recorded a decrease or remained unchanged in the individual gravidtrap index as compared to the Area Gravidtrap Index last month, i.e. August 2025, representing that the areas' mosquito infestation improved or maintained a low level. Seven other areas recorded a slight increase, but the indexes were lower than 10 per cent.

     Public participation is crucial to effective control of mosquito problems. The FEHD appeals to members of the public to continue to work together in strengthening personal mosquito control measures, including:

• tidy up their premises and check for any accumulation of water inside their premises;
• remove all unnecessary water collection and eliminate the sources;
• check household items (those placed in outdoor and open areas in particular), such as refuse containers, vases, air conditioner drip trays, and laundry racks to prevent stagnant water;
• change the water in flower vases and saucers of potted plants at least once every seven days;
• properly cover all containers that hold water to prevent mosquitoes from accessing the water; and
• properly dispose of articles that can contain water, such as empty lunch boxes and cans.

     Starting in August this year, following the completion of the surveillance of individual survey areas, and once the latest gravidtrap index and the density index are available, the FEHD will disseminate the 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 the 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. At present, the FEHD has set up gravidtraps in 64 survey areas of the community. During the two weeks of surveillance, 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 of the two weeks' 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#).

Ends/Thursday, September 11, 2025
Issued at HKT 17:00

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