FEHD releases sixth batch of gravidtrap indexes for Aedes albopictus in April (with photos)
| District | Survey Area | April 2026 | |
| First Phase Gravidtrap Index | First Phase Density Index | ||
| Tuen Mun | Tuen Mun West | 8.0% | 1.0 |
| District | Survey Area | April 2026 | |
| Area Gravidtrap Index | Area Density Index | ||
| Islands | Cheung Chau | 7.3% | 1.6 |
| Kowloon City | Kowloon City | 7.4% | 1.1 |
| Kwun Tong | Kowloon Bay | 9.8% | 1.7 |
| Lam Tin and Sau Mau Ping | 9.4% | 1.3 | |
| Wong Tai Sin | Diamond Hill and Tsz Wan Shan | 8.4% | 1.0 |
| Ngau Chi Wan and San Po Kong | 17.8% | 1.1 | |
| Wong Tai Sin East | 9.8% | 1.3 | |
| Yau Tsim | Tsim Sha Tsui East and King's Park | 2.8% | 1.0 |
| North | Fanling South | 8.4% | 1.1 |
| Sha Tin | Tai Wai | 5.0% | 1.2 |
| Kwai Tsing | Kwai Chung West | 4.5% | 1.0 |
| Tsing Yi South | 8.8% | 1.0 | |
| Tuen Mun | So Kwun Wat | 19.3% | 1.4 |
| Tuen Mun North | 7.3% | 1.2 | |
With reference to the data from the past few years, the gravidtrap indexes start to rise from April or May every year. The actual timing of the increase and its extent are affected by factors like weather and rainfall. The average temperature and rainfall in April this year were higher than those of the same period last year, creating favourable conditions for mosquito growth and breeding and thus leading to the earlier rise of gravidtrap indexes this year, but the overall trend and extent of the increase are similar to those of previous years. In response to the rise of gravidtrap indexes, the FEHD, together with relevant departments and stakeholders, has implemented rapid response measures and deployed targeted actions.
For Ngau Chi Wan and San Po Kong in Wong Tai Sin District, and So Kwun Wat in Tuen Mun District, 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. In particular, the gravidtrap data for Ngau Chi Wan and San Po Kong showed that areas with more mosquito problems included parks, schools and public housing estates, while the gravidtrap data for So Kwun Wat showed that areas with more mosquito problems included parks and private housing estates.
In response to the high-risk areas identified in the said survey areas, the FEHD has issued a statutory notice to a relevant construction site contractor following the discovery of stagnant water at a construction site in So Kwun Wat in Tuen Mun District, requiring the clearance of such item within a specified timeframe. 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 areas to review the effectiveness of the mosquito control work.
The FEHD has so far released six batches of gravidtrap indexes for Aedes albopictus in April 2026, covering 62 survey areas. Among these 62 survey areas, one recorded a decrease or remained unchanged as compared to the Area Gravidtrap Index last month (i.e. March 2026), representing that the area's mosquito infestation improved or maintained a low level. Fifty-one other areas recorded a slight increase, but the indexes were lower than 10 per cent.
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/Tuesday, May 5, 2026
The Food and Environmental Hygiene Department (FEHD) today (May 5) released the sixth batch of gravidtrap indexes and density indexes for Aedes albopictus in April, covering 15 survey areas. Photo shows an FEHD staff member inspecting a construction site in So Kwun Wat, Tuen Mun District. Following the discovery of stagnant water at the construction site, a statutory notice has been issued to the relevant construction site contractor, requiring the clearance of such item within a specified timeframe.
The Food and Environmental Hygiene Department (FEHD) today (May 5) released the sixth batch of gravidtrap indexes and density indexes for Aedes albopictus in April, covering 15 survey areas. Photo shows an FEHD staff member inspecting a new mosquito trap at a public housing estate in Ngau Chi Wan, Wong Tai Sin District, and providing the property management staff members with technical advice on mosquito prevention and control.
The Food and Environmental Hygiene Department (FEHD) today (May 5) released the sixth batch of gravidtrap indexes and density indexes for Aedes albopictus in April, covering 15 survey areas. Photo shows an FEHD staff member inspecting a school in San Po Kong, Wong Tai Sin District, reminding the school's staff member to ensure clearance of surface channels to prevent water accumulation.