The Food and Environmental Hygiene Department (FEHD) today (July 23) announced that the monthly ovitrap index for Aedes albopictus for June rose to 11.3 per cent from 10.2 per cent in May, indicating that mosquito infestation was slightly more extensive in the areas surveyed. The FEHD reminded the public to stay vigilant and keep up effective measures against mosquitoes as the hot and rainy weather of summer is favourable for proliferation of mosquitoes.
"Aedes albopictus is a kind of mosquito that can transmit dengue fever (DF) and Zika virus. In view of the fact that Hong Kong recorded a confirmed local DF case, five local Japanese encephalitis (JE) cases and one imported case of Zika Virus Infection last year and DF is still highly prevalent in neighbouring areas, and that the rainy weather of summer is conducive to massive mosquito breeding, the community must work with the Government to continue to carry out effective mosquito prevention measures," an FEHD spokesman said.
Among the 52 areas surveyed last month, the Area Ovitrap Index (AOI) in 10 areas reached or exceeded the alert level of 20 per cent. They were Tseung Kwan O North (41 per cent), Pok Fu Lam (37.9 per cent), Fanling (31.6 per cent), Sai Wan (30.9 per cent), Lai King (25.5 per cent), Kowloon Bay (25 per cent), Wong Tai Sin Central (23.4 per cent), Tseung Kwan O South (22.6 per cent), Tsing Yi North (22.2 per cent) and Kai Tak North (20 per cent).
The spokesman said, "The FEHD is very concerned about mosquito infestation, and an inter-departmental anti-mosquito response mechanism has been activated in the above-mentioned areas for co-ordinating relevant departments and stakeholders to carry out effective mosquito prevention and control measures. In addition to the routine anti-mosquito programme, the FEHD has also cleared potential mosquito breeding grounds in the public places in the areas and applied appropriate larvicides to stagnant water if and when necessary. It has also handled mosquito complaints promptly and taken out prosecutions under the relevant ordinance against mosquito breeding. 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 July 13), the FEHD had instituted 97 prosecutions for mosquito breeding found in relevant premises under the Public Health and Municipal Services Ordinance (Cap 132), comprising 93 cases involving construction sites and four cases involving other premises.
"The government departments concerned have also stepped up inspections and measures to enhance environmental hygiene in areas within their ambits to eliminate existing and potential mosquito breeding grounds. Relevant departments have individually notified the groups that had voluntarily subscribed to the ovitrap rapid alert system when the AOI reached the alert level of 20 per cent. Subscribers have been invited to post specially designed alert notices in the common parts of their premises to urge occupants and staff to carry out mosquito prevention and control measures promptly."
As for the port areas, the monthly ovitrap index for Aedes albopictus for June also slightly rose to 2.4 per cent from 2 per cent in May.
The spokesman added that the FEHD has increased the number of survey areas from 52 to 57 starting from July this year in order to strengthen dengue vector surveillance. The five additional areas are Central and Admiralty, Yau Tong, Wo Che, Tsuen Wan West and Tuen Mun West.
The FEHD and relevant government departments will also continue to intensify their mosquito prevention and control work covering areas under their purview, and strengthen publicity and education campaigns. The third phase of the territory-wide anti-mosquito campaign will commence on August 13 and last for 10 weeks. During the period, mosquito prevention and control work will be enhanced by the FEHD and relevant government departments. 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. 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.
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.
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 spokesman also reminded travellers to take the following precautionary measures when visiting areas where mosquito-borne diseases are prevalent during the summer 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 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.