The Food and Environmental Hygiene Department (FEHD) today (April 17) released the second batch of gravidtrap indexes and density indexes for Aedes albopictus in April, covering eight survey areas, as follows:
 

District	Survey Area	April 2026
		First Phase Gravidtrap Index	First Phase Density Index
North	Sheung Shui	21.3%	1.2

 

District	Survey Area	April 2026
		Area Gravidtrap Index	Area Density Index
Central and Western	Central and Admiralty	0.0%	N/A
Kowloon City	Hung Hom and To Kwa Wan	6.1%	1.0
Kwun Tong	Yau Tong and Cha Kwo Ling	0.9%	1.0
Sha Tin	Sha Tin East	4.1%	1.4
Kwai Tsing	Tsing Yi North	8.4%	1.1
Tsuen Wan	Ma Wan and Sham Tseng	4.6%	1.0
	Tsuen Wan West	4.0%	1.3

     Among the second batch of First Phase Gravidtrap Indexes covering one survey area and Area Gravidtrap Indexes covering seven survey areas in April, all were below 10 per cent, except for Sheung Shui in North District. 

     For Sheung Shui in North District, which recorded an index exceeding 10 per cent, in accordance with the mechanism implemented by the FEHD in response to the chikungunya fever (CF) situation (i.e. strengthening mosquito control work in areas with a gravidtrap index between 10 per cent and 20 per cent, instead of 20 per cent or above under the original mechanism), the FEHD is collaborating with relevant departments and stakeholders to identify locations with high mosquito infestations and carry out intensive and targeted mosquito control measures. In particular, the gravidtrap data for Sheung Shui showed that areas with more mosquito problems included parks, schools, public housing estates and village houses. The FEHD inspected the survey area today and found mosquitoes breeding in a public housing estate, and filed charges against the relevant property management company. The FEHD and the relevant departments are following up on the mosquito control work, and will also organise exhibitions, distribute leaflets and posters, and notify residential estates that have subscribed to the gravidtrap Rapid Alert System, advising property management agents and residents to stay vigilant and work together in taking mosquito prevention and elimination measures. In addition, the FEHD will strengthen the monitoring of the gravidtrap index in the area to review the effectiveness of the mosquito control work.

     The FEHD has so far released two batches of gravidtrap indexes for Aedes albopictus in April 2026, covering 14 survey areas. Among these 14 survey areas, two recorded a decrease or remained unchanged as compared to the Area Gravidtrap Index last month (i.e. March 2026), representing that the areas' mosquito infestation improved or maintained a low level. Ten other areas recorded a slight increase, but the indexes were lower than 10 per cent.

     The warm and humid weather of spring is favourable for mosquito breeding. Members of the public should strengthen prevention work against mosquito breeding before the rainy season, and eliminate potential mosquito breeding sites in advance, with a view to avoiding the nuisances caused by rapid mosquito breeding during the rainy season and reducing the risk of transmitting mosquito-borne diseases.

     Public participation is crucial to the 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 collections 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 water in flower vases and scrub their inner surfaces thoroughly, and remove water in saucers under potted plants at least once a week;
• properly cover all containers that hold water to prevent mosquitoes from accessing the water;
• properly dispose of articles that can contain water, such as disposable meal boxes and empty cans; and
• scrub drains and surface sewers with alkaline detergent at least once a week to remove any mosquito eggs.

     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 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. At present, the FEHD has set up gravidtraps in 62 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#).

Ends/Friday, April 17, 2026
Issued at HKT 20:55

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