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October's monthly gravidtrap index for Aedes albopictus drops
     The Food and Environmental Hygiene Department (FEHD) today (November 24) announced that the monthly gravidtrap index for Aedes albopictus (MGI) in October is 3.9 per cent, which is far lower than the index of 6.7 per cent in September. The index in October is at Level 1 at its lowest, indicating that mosquito infestation in the areas surveyed was not extensive. Among the 62 survey areas, only the area gravidtrap index (AGI) in Lok Fu West (25.5 per cent) exceeded the alert level of 20 per cent. Moreover, the monthly density index for Aedes albopictus (MDI) in October remained at 1.2 as in September, which represented that an average of 1.2 Aedes albopictus adults were found in the Aedes-positive gravidtraps, indicating that the number of adult Aedes albopictus was not high in the areas surveyed. Despite the drop in the index, given that the autumn in Hong Kong is relatively warm with occasional rain, with the rainfall recorded last month being 40 per cent more than the average for the same month in previous years, which is favourable for mosquito breeding, the FEHD reminded the public to continue to work with the Government to carry out effective mosquito prevention and control measures.

     As for the port areas, the port monthly gravidtrap index in October dropped to 0.4 per cent from 1.1 per cent in September, while the port monthly density index in October also dropped to 1 from 1.2 in September.

     A spokesman for the FEHD said, "In Lok Fu West where the MGI in October exceeded the alert level, the Aedes-positive gravidtraps were found in the vicinity of private residential areas, recreational facilities, schools and public places. The FEHD is very concerned about the mosquito infestation in the area and has enhanced co-operation with the relevant government department and organisations, including promptly notifying relevant government departments to strengthen mosquito prevention and control measures in areas under their purview, conducting fogging to kill adult mosquitoes, cleaning up mosquito breeding places and setting up new mosquito traps."

     The FEHD also commenced the All-out Anti-mosquito Operations earlier. Major anti-mosquito measures include carrying out fogging in scrubby areas within a 100-metre radius around residences 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 strengthen publicity and education campaigns.

     The AGI and the area density index (ADI) indicate the extensiveness of distribution and the density of Aedine mosquitoes respectively in that particular survey area, while the MGI and the MDI are enumerated by pooling together all AGIs and ADIs of the same month, which reflects the general situation of Aedes albopictus in all survey areas. The gravidtrap and density indices for Aedes albopictus in different areas and information on mosquito prevention and control measures are available on the department's website at www.fehd.gov.hk.

     The spokesman said, "Aedes albopictus is a kind of mosquito that can transmit dengue fever (DF) as well as 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. As Hong Kong has recorded this year's first local DF case in April and the dengue activity in neighbouring areas has remained high, and the autumn in Hong Kong is relatively warm with occasional rain which is favourable for mosquito breeding, the public must continue to work with the Government to carry out effective mosquito prevention and control measures."

     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, 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 the public and estate management bodies to keep drains free of blockage and level all defective ground surfaces to prevent 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.

     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.
Ends/Tuesday, November 24, 2020
Issued at HKT 16:00
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