Monthly gravidtrap index for Aedes albopictus mosquitoes in January remains at low level
The Food and Environmental Hygiene Department (FEHD) today (February 5) announced that the monthly gravidtrap index for Aedes albopictus mosquitoes in January was 0.1 per cent, lower than the 0.2 per cent recorded in December 2025, which remained at the lowest Level 1, indicating that the distribution of Aedes albopictus mosquitoes in the areas surveyed was not extensive.
The Food and Environmental Hygiene Department (FEHD), Photo source: FB of FEHD
In January, all 62 survey areas recorded an area gravidtrap index (AGI) lower than the alert level of 20 per cent, and most of the areas recorded 0 per cent. Moreover, the monthly density index for Aedes albopictus in January was 1, which represented that an average of one Aedes albopictus adult was found in the Aedes-positive gravidtraps, indicating that the number of adult Aedes albopictus was not abundant in the survey areas. 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 website at www.fehd.gov.hk.
A spokesman for the FEHD said, "The FEHD has continued to intensify mosquito prevention and control work with relevant government departments in areas under their purview, including eliminating mosquito breeding places, applying larvicides, conducting fogging operations to eradicate adult mosquitoes, and placing mosquito trapping devices at suitable locations. The FEHD has also provided government departments with professional advice and technical support to assist them in swiftly formulating and implementing effective anti-mosquito measures while strengthening publicity and education at the same time. Under the concerted efforts and collaboration of various parties, the index in January remained at a low level. Nevertheless, the breeding and activity of mosquitoes will not stop in winter. The FEHD will continue to monitor the mosquito infestation in all districts and will conduct prompt and effective mosquito prevention and control work."
The FEHD will continue to conduct a three-phase Anti-mosquito Campaign this year. The first phase of the territory-wide campaign will be launched on February 23 and will run until March 20. During the period, the district offices of the FEHD will target residences, schools, construction sites, public housing estates, hospitals, illegal cultivation sites, waterfront public and private cargo working areas, cross-boundary checkpoints, typhoon shelters and cross-boundary ferry terminals, to remove accumulated water and carry out mosquito prevention and control work. Furthermore, the All-out Anti-mosquito Operations, which began on May 7 last year, are still ongoing. The FEHD will continue to collaborate with relevant departments to eliminate potential mosquito breeding sites and eradicate adult mosquitoes by means of regular ultra-low volume fogging operations. The FEHD appeals to property management agents to continue actively participating in the All-out Anti-mosquito Operations.
The FEHD currently makes regular announcements on gravidtrap indexes for Aedes albopictus on its webpage. To allow more citizens to quickly grasp the mosquito infestation situation, the FEHD has strengthened information dissemination by promptly announcing the latest gravidtrap indexes through press releases and social media.
In addition, to further reduce the risk of transmission of chikungunya fever (CF), the FEHD has extended its intensified mosquito control work, which was originally activated when the AGI reaches 20 per cent, to cover areas with the AGI falling between 10 and 20 per cent. Specifically, the FEHD will conduct detailed risk assessments in the areas concerned to identify locations with higher mosquito infestation risks and, in collaboration with relevant departments and stakeholders, conduct intensive and targeted mosquito control work. The FEHD will also notify nearby housing estates, advising property management agents and residents to stay vigilant and work together to take mosquito prevention and elimination measures.
To reduce the risk of transmission of CF and dengue fever (DF), the FEHD continues to step up mosquito prevention and control measures across all districts and conduct vector investigations and targeted mosquito control operations within a 250-metre radius of the residence of patients and the places patients had visited during the infectious period, including removing mosquito breeding grounds, applying larvicides to stagnant water that cannot be cleared, and carrying out ultra-low volume fogging operations in adult mosquito habitats such as densely wooded areas, dark and secluded places, and abandoned structures to eliminate adult mosquitoes.
The FEHD appeals to members of the public to continue to stay alert and work together to carry out mosquito prevention and control measures early, including inspecting their homes and surroundings to remove potential breeding grounds, changing water in vases and scrubbing their inner surfaces, removing water in saucers under potted plants at least once a week, properly disposing of containers such as soft drink cans and lunch boxes. The FEHD also advises members of the public and estate management bodies to keep drains free of blockage and level all defective ground surfaces to prevent the accumulation of water. They should also scrub all drains and surface sewers with an alkaline detergent at least once a week to remove any mosquito eggs.
Aedes albopictus is a kind of mosquito that can transmit DF and CF. DF is commonly found in tropical and subtropical regions of the world, and has become endemic in many countries in Southeast Asia. In 2024, the World Health Organization (WHO) recorded over 14 million DF cases, which was a record number. Furthermore, according to the WHO, CF cases have been recorded in more than 110 countries/regions. Many countries worldwide experienced CF outbreaks last year; as of December 10, 2025, more than 500 000 cases had been reported in over 40 countries/regions worldwide. Cases have been reported in the Americas, Africa, Asia, and Europe. Although the northern hemisphere has entered the winter season, temperatures in subtropical and some temperate regions remain elevated due to climate change, creating favourable conditions for mosquito breeding. In addition, CF outbreaks continue to occur in many countries worldwide. The risk of imported cases persists. Members of the public should check the situation of the destinations before travelling abroad, especially when travelling to Southeast Asian countries.
Photo source: reference image
