FEHD releases second batch of gravidtrap index for Aedes albopictus in August
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| District | Survey Area | August 2025 | |
| First Phase Gravidtrap Index | First Phase Density Index | ||
| Central/Western | Sheung Wan and Sai Ying Pun | 7.3% | 1.5 |
| Wanchai | Happy Valley | 9.6% | 1.0 |
| Mong Kok | Mong Kok | 0.0% | N/A |
| Wong Tai Sin | Wong Tai Sin West | 1.9% | 1.0 |
| Sai Kung | Tseung Kwan O West | 3.6% | 1.0 |
| Tseung Kwan O East | 5.5% | 1.0 | |
| Tseung Kwan O North | 2.3% | 3.0 | |
| North | Sheung Shui | 9.5% | 1.0 |
| Yuen Long | Yuen Long Town | 1.8% | 1.0 |
| Tuen Mun | Tuen Mun North | 3.2% | 1.0 |
In August, all the 10 survey areas covered in the second batch recorded a gravidtrap index level lower than 10 per cent.
The FEHD has so far announced the first and the second batches of the gravidtrap index for Aedes albopictus in August, covering 23 survey areas. Among these 23 survey areas, 17 recorded a decrease in the Gravidtrap Index as compared with the Area Gravidtrap Index in last month, i.e. July 2025, representing improvement in the areas' mosquito infestation condition. The index of one area remained the same, while four areas recorded a slight increase but the index was lower than 10 per cent. In response to the recent chikungunya fever (CF) situation, the FEHD has activated a mechanism that strengthen mosquito control work in areas with the gravidtrap index between 10 per cent and 20 per cent, which was originally activated when the gravidtrap index reaches 20 per cent or above. The FEHD, in collaboration with relevant departments and stakeholders, will strengthen the mosquito elimination work in So Kwun Wat, Tuen Mun, identify locations with high mosquito infestation, and carry out intensive and targeted mosquito control measures. The FEHD will also organise exhibitions, distribute leaflets and posters, and notify the residential estates 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.
The FEHD appeals to members of the public to adopt the following measures, strengthening the prevention against the breeding of mosquitoes:
- Tidy up their premises and check for any accumulation of water in containers inside their premises;
- Remove all unnecessary water collection and eliminate the sources;
- Completely change the water in flower vases at least once a week and remove the water on the plant saucers;
- Properly cover all containers that hold water;
- Properly dispose of refuse, such as soft drink cans, empty bottles and boxes, in covered litter containers; and
- Level irregular ground surfaces and holes.
Starting August this year, following the completion of 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 indices 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, August 11, 2025
Issued at HKT 22:30
Issued at HKT 22:30
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