FEHD releases first batch of gravidtrap indexes for Aedes albopictus in December
The Food and Environmental Hygiene Department (FEHD) today (December 11) released the first batch of gravidtrap indexes and density indexes for Aedes albopictus in December, covering 21 survey areas, as follows:
District
Survey Area
December 2025
First Phase Gravidtrap Index
First Phase Density Index
Eastern
Chai Wan West
0.0%
N/A
North Point
0.0%
N/A
Southern
Aberdeen and Ap Lei Chau
0.0%
N/A
Deep Water Bay and Repulse Bay
0.0%
N/A
Wan Chai
Tin Hau
0.0%
N/A
Wan Chai North
0.0%
N/A
Happy Valley
0.0%
N/A
Yau Tsim
Tsim Sha Tsui
0.0%
N/A
Mong Kok
Mong Kok
0.0%
N/A
Kowloon City
Ho Man Tin
0.0%
N/A
Kai Tak North
2.7%
1.0
Sai Kung
Tseung Kwan O West
0.0%
N/A
Sha Tin
Tai Wai
0.0%
N/A
Sha Tin East
0.0%
N/A
Ma On Shan
1.6%
1.0
Sha Tin Town Centre and Fo Tan
0.0%
N/A
Tai Po
Tai Po East
0.0%
N/A
North
Sheung Shui
0.0%
N/A
Yuen Long
Tin Shui Wai
0.0%
N/A
Tuen Mun
Tuen Mun South
0.0%
N/A
Tsuen Wan
Ma Wan
0.0%
N/A
Among the first batch of First Phase Gravidtrap Indexes covering 21 survey areas in December, all were below 10 per cent.
Among these 21 survey areas, 20 recorded a decrease or remained unchanged in the individual gravidtrap index as compared to the Area Gravidtrap Index last month, i.e. November 2025, representing that the areas' mosquito infestation improved or maintained a low level. Another area recorded a slight increase, but the index was lower than 10 per cent.
The eggs of Aedes albopictus can withstand long periods of desiccation and will hatch when the temperature becomes suitable and water is present. Members of the public should continue to take mosquito control measures during winter to eliminate mosquito eggs.
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 the water in flower vases and clear the water in saucers of potted plants at least once every seven days;
- properly cover all containers that hold water to prevent mosquitoes from accessing the water;
- properly dispose of articles that can contain water, such as empty lunch boxes and cans; and
- scrub drains and surface sewers with alkaline detergent at least once a week to remove any mosquito eggs.
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 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 chikungunya fever (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 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#).
The Food and Environmental Hygiene Department (FEHD)
