The Food and Environmental Hygiene Department (FEHD) today (October 18) announced that the monthly ovitrap index for Aedes albopictus for September dropped to 6 per cent from 7.3 per cent in August. Though there was a decrease in the ovitrap index, the mosquito infestation was still slightly more extensive in the areas surveyed. The FEHD reminded the public to keep up effective prevention and control measures against mosquitoes, as well as to take personal protective measures to reduce the risk of contracting mosquito-borne diseases through mosquito bites.
"Aedes albopictus is a kind of mosquito that can transmit dengue fever (DF) and Zika virus. Hong Kong has recorded 29 local DF cases so far this year. Though there have been no new cases in the past few weeks, as the relatively high temperature of autumn in Hong Kong is favourable for mosquito breeding and DF is also highly prevalent in neighbouring areas, the public must stay alert and work with the Government to continue to carry out effective mosquito prevention and control measures," an FEHD spokesman said.
Among the 57 areas surveyed last month, positive ovitrap indices, ranging from 1.7 per cent to 19 per cent, were recorded in 45 areas, with the highest in Sheung Shui. As for the port areas, the monthly ovitrap index for Aedes albopictus for September also dropped to 1.4 per cent from 2.2 per cent in August.
The spokesman said, "The FEHD is very concerned about mosquito problems. In response to the local DF cases, the FEHD has enhanced the all-out anti-mosquito operations throughout the territory during the third phase of the territory-wide anti-mosquito campaign, including conducting weekly fogging operations to kill adult mosquitoes with a view to reducing the number of adult mosquitoes, carrying out inspection and trimming of grass as well as removing stagnant water, applying insecticide and disposing of abandoned water containers every week to remove the potential habitat of mosquitoes and prevent mosquito breeding. During the period, relevant departments and organisations have also carried out the above-mentioned operations in areas under their purview. In the aftermath of Super Typhoon Mangkhut, the FEHD spared no efforts in removing typhoon debris and fallen twigs and leaves, and at the same time stepped up clearance of stagnant water and rubbish to eliminate mosquito breeding grounds. The further decrease in September's monthly index showed that the relevant operations were effective in controlling and preventing mosquitoes.
"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 district offices of the FEHD will continue to 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 to intensify mosquito prevention and control work. The FEHD will, immediately after each phase of the campaign, conduct special territory-wide thematic mosquito prevention and control operations so as to enhance the effectiveness of the campaign."
In addition, the FEHD set up four Pest Control Inspection Teams in May last year to step up inspection of construction sites and enforcement action against mosquito breeding. This year (as at October 7), the FEHD had instituted 170 prosecutions for mosquito breeding found in relevant premises under the Public Health and Municipal Services Ordinance (Cap 132), comprising 161 cases involving construction sites and nine cases involving other premises.
In order to keep the public abreast of the latest situation of mosquito infestation and assist them to take timely mosquito prevention and control measures, the FEHD is releasing additional results of the Area Ovitrap Index (AOI) for Aedes albopictus at two more stages every month, apart from the announcement of the monthly AOI and the monthly ovitrap index for Aedes albopictus. The FEHD will follow the established practice of notifying relevant government departments of the aforementioned indices so that they can carry out targeted mosquito prevention and control work promptly to strengthen the anti-mosquito efforts. As the survey for the ovitrap index in September was affected by the typhoon, only one set of additional AOI results was available in the month.
　
The spokesman added that as Aedes albopictus breeds in small water bodies, members of the public should continue to carry out effective mosquito prevention and control measures, including inspecting their homes and surroundings to remove potential breeding grounds, scrubbing vases and pot plant saucers 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 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 follow 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 effort of all parties concerned. The community must work together with the Government to carry out 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 57 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 activity of Aedes albopictus outside the 57 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 mosquito prevention and control measures are available on the department website at www.fehd.gov.hk.
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