Mosquito Index Drops to Record Low, FEHD Intensifies Prevention Efforts

Monthly gravidtrap index for Aedes albopictus mosquitoes in February remains at lowest level

The Food and Environmental Hygiene Department (FEHD) today (March 9) announced that the monthly gravidtrap index for Aedes albopictus mosquitoes in February dropped further to 0.03 per cent, from 0.1 per cent in January. The index in February remained at the lowest Level 1, indicating that the distribution of Aedes albopictus mosquitoes in the areas surveyed was not extensive.

In February, 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 zero per cent. Moreover, the monthly density index for Aedes albopictus in February 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 February remained at a low level. Nevertheless, the warm and humid weather of spring is favourable for mosquito breeding. The FEHD will continue to monitor the mosquito infestation in all districts and will carry out prompt and effective mosquito prevention and control work."

The FEHD continues to conduct a three-phase Anti-mosquito Campaign this year. The first phase of the territory-wide campaign was 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, land boundary control points, typhoon shelters and cross-boundary ferry terminals, to remove accumulated water and carry out mosquito prevention and control work. Furthermore, the second phase of All-out Anti-mosquito Operations, which began on May 7 last year, is 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 indices 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 indices 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 that 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 empty cans and disposable meal 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.

Source: AI-found images

DH announces latest situation regarding Legionnaires' disease cases

The Centre for Health Protection (CHP) of the Department of Health (DH) today (March 9) reported the latest number of Legionnaires' disease (LD) cases, and reminded the public of the importance of using and maintaining properly designed man-made water systems, adding that susceptible groups should strictly observe relevant precautions.

From March 1 to 7, the CHP recorded two community-acquired LD cases. The details of the cases are as follows:

1. a 39-year-old female patient with good past health living in Yau Tsim Mong District; and

2. an 89-year-old male patient with underlying illnesses living in Kwun Tong District.

The CHP is conducting epidemiological investigations to identify the potential sources of infection and high-risk exposure. An initial investigation revealed that these are sporadic cases. No epidemiological linkages have been established between these cases and other confirmed cases previously recorded in Hong Kong.

As of March 7, 13 LD cases had been recorded this year. In 2025 and 2024, there were 167 and 135 LD cases respectively.

Men, people aged over 50, smokers, alcoholics and persons with weakened immunity are more susceptible to LD. Some situations may also increase the risk of infection, including poor maintenance of water systems; living in areas with old water systems, cooling towers or fountains; using electric water heaters, whirlpool spas or hot water spring spas; and recent stays in hotels or ships.

Legionellae are found in various environmental settings and grow well in warm water (20 to 45 degrees Celsius). They can be found in aqueous environments such as water tanks, hot and cold water systems, cooling towers, whirlpool spas, water fountains, humidifiers and home respiratory devices that support breathing. People may become infected when they breathe in contaminated droplets (aerosols) and mist generated by artificial water systems, or when handling garden soil, compost and potting mixes.

Immunocompromised persons should:

Use sterile or boiled water for drinking, tooth brushing and mouth rinsing;

Avoid using humidifiers, or other mist- or aerosol-generating devices; and

If using humidifiers, or other mist- or aerosol-generating devices, fill the water tank with only sterile or cooled freshly boiled water, and not water directly from the tap. Also, clean and maintain humidifiers/devices regularly according to manufacturers' instructions. Never leave stagnant water in a humidifier/device. Empty the water tank, wipe all surfaces dry, and change the water daily.

The public should observe the health advice below:

Observe personal hygiene;

Do not smoke and avoid alcohol consumption;

Strainers in water taps and shower heads should be inspected, cleaned, descaled and disinfected regularly or at a frequency recommended by the manufacturer;

If a fresh-water plumbing system is properly maintained, it is not necessary to install domestic water filters. Use of water filters is not encouraged as clogging occurs easily, which can promote growth of micro-organisms. In case water filters are used, the pore size should be 0.2 micrometres (µm) or less and the filter needs to be changed periodically according to the manufacturer's recommendations;

Drain and clean water tanks of buildings at least quarterly;

Drain or purge for at least one minute infrequently used water outlets (e.g. water taps, shower heads and hot water outlets) and stagnant points of the pipework weekly or before use;

Seek and follow doctors' professional advice regarding the use and maintenance of home respiratory devices and use only sterile water (not distilled or tap water) to clean and fill the reservoir. Clean and maintain the device regularly according to the manufacturer's instructions. After cleaning/disinfection, rinse the device with sterile water, cooled freshly boiled water or water filtered with 0.2 µm filters. Never leave stagnant water in the device. Empty the water tank, keep all surfaces dry, and change the water daily; and

When handling garden soil, compost and potting mixes:

Wear gloves and a face mask;

Water gardens and compost gently using low pressure;

Open composted potting mixes slowly and make sure the opening is directed away from the face;

Wet the soil to reduce dust when potting plants; and

Avoid working in poorly ventilated places such as enclosed greenhouses.

The public may visit the CHP'sLD page, theCode of Practice for Prevention of LDand theHousekeeping Guidelines for Cold and Hot Water Systems for Building Managementof the Prevention of LD Committee, and the CHP'srisk-based strategyfor prevention and control of LD.

Additionally, as smokers and alcoholics are more susceptible to LD, the Government urgesmembers of the public to quit smoking and avoid drinking. Members of the public may call the DH Integrated Smoking Cessation Hotline at 1833 183, which is answered by registered nurses who provide professional counselling and referral to a wide range of free smoking cessation services. The public may also visit the smoking cessation thematic website (www.livetobaccofree.hk) for more information on smoking cessation. The DH has also launched the Pilot Alcohol Cessation Counselling Service, which provides free counselling to people identified as having probable alcohol dependence, through a subvented non-governmental organisation, the Tung Wah Group of Hospitals (TWGHs). Information on the service has been uploaded to the DH'sChange for Healthwebsite. Eligible persons who are interested can call the enquiry hotline of the TWGHs (2884 9876).

Source: AI-found images