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September's monthly ovitrap index for Aedes albopictus edges down further

     The Food and Environmental Hygiene Department (FEHD) announced today (October 22) that the monthly territory-wide ovitrap index for Aedes albopictus, a kind of mosquito which can transmit dengue fever, dropped from 6.3 per cent in August to 3.9 per cent in September, indicating that the infestation of Aedes albopictus in the area surveyed stayed at a relatively low level and the infestation of the vector is not extensive.

     An FEHD spokesman said, "The levels of infestation in different areas vary. Among the 44 areas surveyed last month, positive ovitrap indices were recorded in 34 areas, ranging from 1.8 per cent to 11.3 per cent, with the highest in Ho Man Tin and Yuen Chau Kok. As for the port areas, the monthly ovitrap index for Aedes albopictus for September also fell to 0.3 per cent from 1.3 per cent in August.

     "Despite the recent cooler weather, the public should keep up anti-mosquito measures and stay alert to the risk of mosquito-transmitted diseases," he stressed.

     The spokesman also advised that the public and estate management bodies should 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. After rainfall, water should be immediately removed from balconies, rooftops and courtyards.

     "People should inspect their homes and surroundings to remove all the 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 added.

     The ovitrap index is divided into four levels, reflecting the infestation level of the 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.

     Oviposition traps are set in 44 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 daytime. The index does not capture the activities of Aedes albopictus outside the 44 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/Wednesday, October 22, 2014
Issued at HKT 16:03


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