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Public urged to keep up anti-mosquito efforts
     The Food and Environmental Hygiene Department (FEHD) today (April 24) announced that the monthly ovitrap index for Aedes albopictus for March rose to 0.8 per cent from 0.1 per cent in February, indicating that the infestation of Aedes albopictus in the areas surveyed was not extensive. Nevertheless, in view of the first local dengue fever (DF) case recorded in April this year, and that the warm and humid weather of spring is favourable for large-scale mosquito breeding in a short period of time, the FEHD reminds the public to carry out effective prevention and control measures against mosquitoes early before the onset of the rainy season. Relevant government departments have also commenced the All-out Anti-mosquito Operations on April 15 to enhance anti-mosquito work throughout the territory. Meanwhile, starting from this month, the FEHD will, in addition, release the density index, as derived from the newly designed gravidtraps, to indicate the density of adult Aedes albopictus in the surveyed areas.

     Among the 57 areas surveyed last month, positive ovitrap indices, ranging from 0.8 per cent to 6.7 per cent, were recorded in 25 areas. As for the port areas, the monthly ovitrap index for Aedes albopictus for March rose slightly to 0.05 per cent from zero in February.

     A spokesman for the FEHD said, "Aedes albopictus is a kind of mosquito that can transmit dengue fever as well as the Zika virus infection. DF is commonly found in tropical and subtropical regions of the world, and has become endemic in many countries in Southeast Asia. The World Health Organization also issued warnings that the number of DF cases recorded in Asia last year was higher than before. Hong Kong has recorded the first local DF case this year in this month and the dengue activity in neighbouring areas has remained high. The relatively high temperature in spring coupled with the approach of the rainy season is conducive to the proliferation of mosquitoes and the community must remain vigilant and continue to take effective mosquito control measures."

     The spokesman said that relevant government departments have enhanced co-operation to eliminate potential breeding places for mosquitoes ahead of the rainy season, and commenced the All-out Anti-mosquito Operations on April 15 which will run until the end of the rainy season to start the fogging operations specifically at risky areas to eradicate adult mosquitoes.

     The spokesman said, "The major anti-mosquito measures of the All-out Anti-mosquito Operations include carrying out fogging in the scrubby areas within a 100-metre radius around residences weekly to kill adult mosquitoes; carrying out inspections, removing stagnant water, applying insecticide and disposing of abandoned water containers weekly to prevent mosquito breeding; and trimming of grass to discourage resting of adult mosquitoes on the site. The FEHD and relevant government departments will continue the above mosquito prevention and control work in areas under their purview, and will strengthen publicity and education campaigns in the coming months. In addition, the FEHD has also started the second phase of its Anti-mosquito Campaign on April 20 which lasts until June 19. During the period, the district offices of the FEHD have targeted areas which have drawn particular concern, such as locations in close proximity to human residences, schools, construction sites, public housing estates, hospitals, illegal cultivation sites, waterfront public and private cargo handling areas, cross boundary check points, typhoon shelters and cross boundary ferry terminals to remove accumulations of water and carry out mosquito prevention and control work. The FEHD will, after the second phase of the campaign, conduct territory-wide thematic mosquito prevention and control special operations so as to enhance the effectiveness of the campaign."

     To better quantify the activities level of Aedes albopictus, and to enable various departments to grasp mosquito infestation conditions and conduct more targeted preventive and control measures, the FEHD has put in place about 5 000 newly designed gravidtraps across the territory starting from this month as a replacement for the ovitraps currently in use to trap and directly count the number of adult mosquitoes. The FEHD will release the new gravidtrap index from April so as to replace the ovitrap index to reflect the distribution of Aedes albopictus. The FEHD will also release a new index, namely the density index, to indicate the density of adult Aedes albopictus in the surveyed area. As the number of adult mosquitoes can be counted directly from the newly designed gravidtrap, and thus there is no need to wait for the hatching of eggs or larvae, the time required for releasing the gravidtrap index and density index for individual surveyed areas will be about two weeks, which is shorter than the time required for releasing the existing ovitrap index which takes about three weeks.

     The spokesman added that as Aedes albopictus breeds in small water bodies, members of the public should carry out effective mosquito prevention and control measures including inspecting their homes and surroundings to remove potential breeding grounds, changing the water in vases and scrubbing the inner surfaces as well as removing the 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. He also advised public and estate management bodies to keep drains free of blockage and level all defective ground surfaces to prevent accumulations 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.

     In addition, rural areas and the vicinity of shrubby areas are natural habitats for mosquitoes, other insects and animals. Members of the public living in rural areas may install mosquito screens on windows and doors if necessary. Those staying in the natural environment should take appropriate personal protective measures against mosquitoes, such as avoiding staying in the vicinity of shrubby areas for a long time, wearing light-coloured long-sleeved clothes and trousers and applying DEET-containing insect repellent. Members of the public are reminded to make reports to relevant government departments via 1823 if mosquito problems are detected.

     The spokesman reiterated that effective mosquito control requires the sustained effort of all parties concerned. The community must work together with the Government to carry out effective mosquito control measures.
     The ovitrap indices for Aedes albopictus in different areas and information on mosquito prevention and control measures are available on the department website at www.fehd.gov.hk. Details of the gravidtrap index and the density index will be released on the website later this month.
Ends/Friday, April 24, 2020
Issued at HKT 16:00
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