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Ovitrap index for Aedes albopictus remains at zero in March

     The Food and Environmental Hygiene Department (FEHD) today (April 22) reminded the public to keep up effective measures against mosquitoes despite the fact that the ovitrap index for Aedes albopictus remained at zero last month. Though the infestation of Aedes albopictus in the areas surveyed stayed at a relatively low level and the infestation of the vector is not extensive, the public should stay alert as the warm and rainy weather of spring is favourable for massive mosquito breeding in a short period of time.
     "Both the monthly territory-wide and port ovitrap indices for Aedes albopictus for March remained at zero, as in January and February," an FEHD spokesman said.

     "Aedes albopictus is a kind of mosquito that can transmit dengue fever (DF). Despite the zero index for Aedes albopictus recorded in March, in view of the confirmation of two local DF cases last year and the fact that DF is still highly prevalent in neighbouring areas, and that Aedes albopictus can also transmit Zika virus, the community must remain vigilant and work together with the Government in sustaining our anti-mosquito work. Moreover, as higher temperatures and more rainfall are expected this spring, which is favourable for mosquito breeding and will lead to an increase in the activity of mosquito-borne diseases, the FEHD and relevant government departments will continue to intensify their mosquito preventive and control work, as well as strengthen publicity and education campaigns," he said.

     "To heighten public awareness of the potential risk of mosquito-borne diseases, including DF and Zika Virus Infection, the FEHD is conducting a three-phase territory-wide Anti-mosquito Campaign this year. The second phase of the Campaign, lasting for 10 weeks, will be launched on April 25. During the period, the district offices of the FEHD will target areas which have 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, and intensify mosquito prevention and control work at those places. In addition, the FEHD will, immediately after each phase of the campaign, conduct thematic mosquito prevention and control special operations across the territory to keep up the effectiveness of the campaign.

     "At the approach of the rainy season, the FEHD and relevant government departments are also conducting, from April 18 to May 22, two rounds of intensive mosquito preventive and control exercises across the territory covering areas under their purview. During the two exercises, actions are taken to kill adult mosquitoes, clear stagnant water and conduct grass cutting to eliminate potential mosquito breeding grounds, as well as to enhance publicity and public education on mosquito control via various channels. With each exercise lasting for two weeks, we hope that mosquitoes of a whole generation, including those that may be infected with DF, will be eliminated," the spokesman added.

      As Aedes albopictus breeds in small water bodies, the spokesman reminded members of the public to inspect their homes and surroundings to remove potential breeding grounds, scrub vases and pot plant saucers at least once a week, properly dispose of containers such as soft drink cans and lunch boxes, and drill large holes in unused tyres. He also advised the public and estate management bodies to keep drains free of blockage and fill up all depressions to prevent puddles from forming. They should also scrub all drains and surface sewers with an alkaline detergent compound at least once a week to remove any mosquito eggs. Members of the public are reminded to make reports to the government departments via 1823 if mosquito problems are detected.

     The spokesman reiterated that effective mosquito control requires the sustained efforts of all parties concerned. The community must work together with the Government to take effective mosquito control measures.
     The ovitrap index is divided into four levels, reflecting the infestation level of Aedes albopictus. Level 1 (< 5 per cent) indicates that infestation of the mosquito is not extensive in the area surveyed. Level 2 (5 per cent - < 20 per cent) indicates that infestation of the mosquito is slightly more extensive in the area surveyed. Level 3 (20 per cent - < 40 per cent) indicates that infestation of the mosquito exceeds one-fifth of the area surveyed. Level 4 (>/= 40 per cent) indicates that almost half of the surveyed area is infested with the mosquito. The Government will step up the scale of anti-mosquito operations according to the level of infestation as well as reports from front-line staff and the public.

     Oviposition traps are set in 52 areas in Hong Kong for monitoring the breeding of Aedes albopictus, which is only one of the mosquito species commonly found in Hong Kong and is active only in the daytime. The index does not capture the activities of Aedes albopictus outside the 52 areas and it also does not measure the prevalence of other kinds of mosquitoes.

     The ovitrap indices for Aedes albopictus in different areas and information on anti-mosquito measures are available on the department website at

Ends/Friday, April 22, 2016
Issued at HKT 16:37


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