The Food and Environmental Hygiene Department (FEHD) today (June 1) released the sixth batch of gravidtrap indexes and density indexes for Aedes albopictus in May, covering 19 survey areas, as follows:
 

District	Survey Area	May 2026
		First PhaseGravidtrap Index	First PhaseDensity Index
Central and Western	Central and Admiralty	13.2%	1.4
Southern	Deep Water Bay and Repulse Bay	13.3%	1.5
Kowloon City	Kai Tak	14.9%	1.1
Wong Tai Sin	Diamond Hill and Tsz Wan Shan	18.3%	1.0
Sha Tin	Sha Tin East	20.3%	1.2
Kwai Tsing	Kwai Chung East	9.5%	2.0
	Kwai Chung West	17.8%	1.0
	Lai King	27.8%	1.5
	Tsing Yi North	33.3%	1.3
Tsuen Wan	Tsuen Wan West	37.7%	1.2
Tuen Mun	Tuen Mun West	18.8%	1.3

 

District	Survey Area	May 2026
		Area Gravidtrap Index	Area Density Index
Central and Western	Sheung Wan and Sai Ying Pun	20.5%	1.9
Kowloon City	Hung Hom and To Kwa Wan	17.2%	1.7
Kwun Tong	Kowloon Bay	28.9%	1.8
Wong Tai Sin	Ngau Chi Wan and San Po Kong	14.7%	1.9
Sai Kung	Sai Kung Town	22.1%	1.4
Tai Po	Tai Po East	10.2%	1.1
Tuen Mun	So Kwun Wat	20.5%	1.3
Yuen Long	Hung Shui Kiu and Ping Shan	14.3%	1.3

     With reference to the data from the past few years, the gravidtrap indexes start to rise from April or May every year. The indexes are higher from April to June. The actual timing and extent of the rise are affected by factors like weather conditions and rainfall. As compared with last year, the temperature began to climb earlier this year and the rainfall in April and May increased substantially, creating favourable conditions for mosquito growth and breeding. As a result, the rise in gravidtrap indexes occurred earlier this year. Depending on factors like rainfall, the indexes may rise further but the overall trend of gravidtrap indexes this year is similar to those of previous years.

     For survey areas which recorded indexes 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. The FEHD has initiated four prosecutions against the relevant construction site contractor, estate management companies and a property management company following the discovery of mosquito breeding at a construction site, two public housing estates and a private housing estate in Central and Western District, Kwun Tong District, Sai Kung District and Tsuen Wan District. Moreover, following the discovery of stagnant water or stagnant water containers in six parks, four construction sites, 15 public housing estates, eight private housing estates and four private premises in Central and Western District, Kowloon City District, Kwun Tong District, Wong Tai Sin District, Sai Kung District, Sha Tin District, Tai Po District, Kwai Tsing District, Tsuen Wan District and Yuen Long District, the FEHD has issued 37 statutory notices to the responsible persons-in-charge, requiring the clearance of such items within a specified timeframe. The FEHD, the relevant departments and stakeholders 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 areas to review the effectiveness of the mosquito control work.

     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 the 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/Monday, June 1, 2026
Issued at HKT 21:20

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