November’s monthly gravidtrap index for Aedes albopictus mosquitoes drops from October level
The Food and Environmental Hygiene Department (FEHD) today (December 11) announced that the monthly gravidtrap index for Aedes albopictus mosquitoes in November dropped to 0.6 per cent from 2 per cent in October, which remained at the lowest Level 1, indicating that the distribution of Aedes albopictus mosquitoes in the areas surveyed was not extensive.
In November, all the 64 survey areas were recorded with a gravidtrap index lower than the alert level of 20 per cent. Moreover, the monthly density index for Aedes albopictus in November was 1.1, which represented that an average of 1.1 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 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, "In response to the latest recorded local case of dengue fever (DF), the FEHD and relevant government departments have intensified mosquito prevention and control work in the residence, workplace and locations visited by a patient during the incubation period and after illness onset, 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, in order to reduce the risk of DF transmission. Under the concerted efforts and collaboration of various parties, the index in November remained at the lowest level. 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 has conducted a three-phase Anti-mosquito Campaign this year. The third phase of the territory-wide campaign, lasting 12 weeks, was conducted from August 5 to October 27. During the period, the district offices of the FEHD targeted areas that had drawn particular concern, such as public markets, cooked food centres and hawker bazaars, single-block buildings, streets and back lanes, common parts of buildings, village houses, construction sites, vacant sites and road works sites, 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 carried out the second phase of the All-out Anti-mosquito Operations since May 2 to focus on intense adult mosquito control by means of regular ultra-low volume fogging operations to continue to eliminate potential mosquito breeding places, and called on property management offices to arrange necessary repairs to their premises to minimise mosquito breeding places. As the weather has turned cooler and drier, the All-out Anti-mosquito Operations launched since March 26 this year will end on December 30. Although the index remains at a low level, the breeding and activity of mosquitoes will not stop in winter. The FEHD advises members of the public to continue routine mosquito prevention and control work to reduce the chance of mosquito breeding when the rainy season approaches.
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, and drilling large holes in unused tyres. 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. DF is commonly found in tropical and subtropical regions of the world, and has become endemic in many countries in Southeast Asia. Based on the latest surveillance data from the Centre for Health Protection of the Department of Health, there has been an increase in DF cases in some places in Asia thus far, compared with the corresponding period of last year. The World Health Organization has recorded over 13 million cases, which is a record number, since the beginning of 2024. Although the number of DF cases recorded in Guangdong Province in the past few months remained at a high level, and most of the cases were locally acquired infection, the number of local DF cases has been decreasing gradually, from over 1 200 cases a week (November 4 to 10) to around 500 cases a week (November 18 to 24), according to the Guangdong Provincial Center for Disease Control and Prevention. Hong Kong has recorded 152 imported DF cases and five local DF cases so far this year. Members of the public should continue to carry out effective mosquito prevention and control measures proactively.
