Public urged to strengthen anti-mosquito efforts early
The Food and Environmental Hygiene Department (FEHD) today (May 8) announced that the monthly gravidtrap index for Aedes albopictus mosquitoes in April was 7.9 per cent, at Level 2, indicating that the distribution of Aedes albopictus mosquitoes in the survey areas was fairly extensive. The FEHD and relevant government departments have stepped up mosquito prevention and control actions.
In April, among the 62 survey areas, the area gravidtrap indexes (AGI) in Tai Po East, Tai Po District, and Sheung Shui, North District, exceeded 20 per cent, reaching the Level 3 alert level. The gravidtraps were mostly located in the vicinity of private residential areas, public housing estates, schools, hospitals, recreational and sports facilities and public places. The FEHD has collaborated with relevant government departments by taking immediate actions to strengthen mosquito prevention and control work in the areas concerned.
Moreover, the monthly density index for Aedes albopictus in April was 1.3, which represented that an average of 1.3 Aedes albopictus adults were 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 indexes 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, "With reference to the data from the past few years, the gravidtrap indexes start to rise from April or May every year. The actual timing of the increase and its extent are affected by factors like weather and rainfall. The average temperature and rainfall in April this year were higher than those of the same period last year, creating favourable conditions for mosquito growth and breeding and thus leading to the earlier rise of gravidtrap indexes this year, but the overall trend and extent of the increase are similar to those of previous years. In response to the rise of gravidtrap indexes, the FEHD, together with relevant departments and stakeholders, has implemented rapid response measures and deployed targeted actions. The FEHD has continued to intensify the 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 conducted site inspections with relevant departments, and provided them with professional advice and technical support to assist them in formulating and implementing effective anti-mosquito measures swiftly. At the same time, the FEHD has strengthened publicity and education. 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 continues to conduct a three-phase Anti-mosquito Campaign this year. The second phase began on April 13 and will run until June 12. During the period, the district offices of the FEHD are targeting 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. To further enhance the effectiveness of mosquito control, the FEHD and relevant government departments have launched phase one and phase two of the All-out Anti-mosquito Operations on March 25 and April 30 respectively. Departments will continue with the work of phase one including eliminating potential mosquito breeding places and arranging for necessary structural repairs to minimise mosquito breeding places, and have already started the work of phase two to conduct regular ultra-low volume fogging operations at places with mosquito infestation to control the mosquitoes. The FEHD called on property management entities 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 that patients had visited during the infectious period. Actions include 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 plant pots 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. 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 their destinations before travellng abroad, especially when travelling to Southeast Asian countries.
Source: AI-found images
