Monthly ovitrap index for Aedes albopictus of December 2016 remains at low level

     The Food and Environmental Hygiene Department (FEHD) announced today (January 23) that the monthly territory-wide ovitrap index for Aedes albopictus dropped from 0.7 per cent in November to 0.1 per cent in December last year, indicating that the infestation of Aedes albopictus in the areas surveyed stayed at a relatively low level and the infestation of the vector is not extensive. 
     "Aedes albopictus is a kind of mosquito that can transmit dengue fever (DF) and Zika virus. Despite the relatively low level of the monthly ovitrap index for Aedes albopictus recorded in December last year, in view of the fact that four local DF cases and two imported cases of Zika Virus Infection were recorded in Hong Kong last year and similar infection cases were reported in neighbouring areas where DF has also remained highly prevalent, and that the breeding and activity of mosquitoes continue in the winter season as cold weather only lasts for a short period of time in Hong Kong, the community must remain vigilant and continue to carry out effective mosquito control measures," an FEHD spokesman said. 
     "With the approach of the Lunar New Year, the public should also carry out anti-mosquito measures during the year-end clean-up to minimise the risk of mosquito-borne diseases. 
      "The FEHD and relevant government departments will continue to intensify their mosquito prevention and control work covering areas under their purview and strengthen publicity and education campaigns. The year-end clean-up operation commenced on January 3 this year, during which mosquito control work is enhanced. The district offices of the FEHD has targeted areas which have drawn particular concern, such as single-block buildings, village houses, construction sites, areas previously detected with local DF cases and different port areas such as container terminals and cargo working areas, and intensified mosquito prevention and control work at those places in winter." 
     The spokesman said that among the 52 areas surveyed last month, positive ovitrap indices were recorded in three areas, ranging from 1.7 per cent to 1.9 per cent, with the highest in Tuen Mun South. As for the port areas, the monthly ovitrap index for Aedes albopictus for December fell to 0 per cent from 0.1 per cent in November. 
     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 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.
     In addition, rural areas and the vicinity of shrubby areas are the 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 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. 
     As Aedes albopictus can transmit DF and Zika virus, oviposition traps are set in 52 areas in Hong Kong for monitoring the breeding of Aedes albopictus, which is one of the mosquito species commonly found in Hong Kong and is active only in the daytime. The index does not capture the activity of Aedes albopictus outside the 52 areas and it also does not measure the prevalence of other kinds of mosquitoes. 
     Moreover, the spokesman reminded travellers to take the following precautionary measures when visiting areas where mosquito-borne diseases are prevalent during the Lunar New Year holidays: 
     * Wear light-coloured, long-sleeved clothes and trousers;
     * Use insect repellents over exposed parts of the body when outdoors; and
     * Use mosquito screens or nets when a room is not air-conditioned. 
     Travellers returning from these places should seek medical advice if they have symptoms such as fever, severe headache or muscle and joint pain. They should also inform their doctor of their travel history. 
     The ovitrap indices for Aedes albopictus in different areas and information on anti-mosquito measures are available on the department website at

Ends/Monday, January 23, 2017
Issued at HKT 14:30