FEHD releases ninth batch of gravidtrap indexes for Aedes albopictus in August (with photos)
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| District |
Survey Area |
August 2025 | |
| First Phase Gravidtrap Index | First Phase Density Index | ||
| Eastern |
Chai Wan West |
3.5% |
1.0 |
| Kowloon City | Hung Hom | 5.5% | 1.0 |
| North | Fanling | 1.9% | 1.0 |
| Yuen Long | Tin Shui Wai | 6.3% | 1.0 |
| Yuen Kong | 0.0% | N/A | |
| Tuen Mun | Tuen Mun South | 7.5% | 1.0 |
| Tsuen Wan |
Tsuen Wan Town |
8.9% |
1.4 |
| Tsuen Wan West |
5.7% |
1.3 |
|
| District |
Survey Area |
August 2025 | |
| Area Gravidtrap Index | Area Density Index | ||
| Central/ Western |
Sai Wan |
7.4% |
1.3 |
| Southern | Aberdeen and Ap Lei Chau | 4.7% | 1.0 |
| Wanchai | Tin Hau | 4.5% | 1.2 |
| Kowloon City |
Lok Fu West |
5.8% |
1.1 |
| Kai Tak North |
12.3% |
1.3 |
|
| Sha Tin |
Sha Tin Town Centre and Fo Tan |
5.0% |
1.0 |
| Yuen Long | Ki Lun Shan | 2.0% | 1.0 |
| Sung Shan | 4.2% | 1.0 | |
| Tsuen Wan | Ma Wan | 14.0% | 1.3 |
Among the ninth batch of First Phase Gravidtrap Indexes covering eight survey areas and Area Gravidtrap Indexes covering nine survey areas in August, all were below 10 per cent, except the Area Gravidtrap Indexes for Kai Tak North in Kowloon City District and Ma Wan in Tsuen Wan District.
For Kai Tak North in Kowloon City District and Ma Wan in Tsuen Wan District, which recorded an index over 10 per cent, in accordance with the mechanism implemented by the FEHD in response to the recent 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 Kai Tak North indicated that areas with more mosquito problems included public housing estates, and the Area Gravidtrap Index for Kai Tak North survey area dropped from 15.9 per cent in July to 12.3 per cent in August. The gravidtrap data for Ma Wan indicated that areas with more mosquito problems include parks, and the gravidtrap index for Ma Wan survey area dropped from 30.4 per cent, which was the highest in the first phase of July, to 14 per cent in August. The relevant departments and stakeholders are actively following up on the mosquito control work. The FEHD will also organise exhibitions, distribute leaflets and posters, and notify the residential estates that have subscribed to the gravidtrap Rapid Alert System, advising property management agents and residents to stay vigilant and join hands in taking mosquito prevention and elimination measures. In addition, the FEHD will strengthen the monitoring of the gravidtrap indexes in those two areas to review the effectiveness of the mosquito control work.
The FEHD has so far released nine batches of gravidtrap indexes for Aedes albopictus in August 2025, covering 59 survey areas. Among these 59 survey areas, 38 recorded a decrease or remained unchanged in the individual gravidtrap index as compared to the Area Gravidtrap Index last month, i.e. July 2025, representing that the areas' mosquito infestation improved or maintained a low level. Fifteen 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 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, August 28, 2025
Issued at HKT 19:10
Issued at HKT 19:10
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