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October's monthly ovitrap index for Aedes albopictus drops further

     The Food and Environmental Hygiene Department (FEHD) announced today (November 23) that the monthly territory-wide ovitrap index for Aedes albopictus dropped from 5.1 per cent in September to 3.3 per cent in October, indicating that the infestation of Aedes albopictus in the areas surveyed is not extensive.

     "Aedes albopictus is a kind of mosquito which can transmit dengue fever (DF). Despite the relatively lower index levels for Aedes albopictus recorded in October, the community must remain vigilant as DF has remained highly prevalent in neighbouring areas. Moreover, we anticipate a warmer winter this year and the dengue activity might increase. The community must continue to carry out effective mosquito control measures to prevent local transmission of DF," an FEHD spokesman said.

     "The FEHD and relevant government departments will continue to intensify their mosquito preventive and control work, as well as strengthen publicity and education campaigns. The FEHD, together with other government departments, launched a city-wide thematic mosquito prevention and control special operation on October 19, which will be extended throughout the winter season and last till January 14, 2016. Mosquito control work will also be enhanced during the year-end clean-up operation, which is due to commence on January 15, 2016. The district offices of the FEHD will target areas which have drawn particular concern, such as single-block buildings, village houses, construction sites and cargo/container terminals and handling areas at port areas, and intensify mosquito prevention and control work at those places," he said.

     The spokesman said that among the 52 areas surveyed last month, the indices of 32 areas recording positive indices ranged from 1.7 per cent to 18.5 per cent, with the highest in Kowloon Bay. As for the port areas, the monthly ovitrap index for Aedes albopictus for October fell to 0.4 per cent from 1.3 per cent in September.

     As Aedes albopictus breeds in small water bodies, the spokesman advised the public and estate management bodies to scrub all drains and surface sewers with an alkaline detergent compound at least once a week to remove any mosquito eggs. They should also keep drains free of blockage and fill up all depressions to prevent puddles from forming. He also reminded 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. 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 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/Monday, November 23, 2015
Issued at HKT 16:01


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