July's monthly ovitrap index for Aedes albopictus edges up

     The Food and Environmental Hygiene Department (FEHD) announced today (August 25) that the monthly ovitrap index for Aedes albopictus for July rose slightly to 10.6 per cent from 10.2 per cent in June, indicating that mosquito infestation was still slightly more extensive in the areas surveyed. The accumulated rainfall recorded in the first seven months of this year was nearly 20 per cent above normal with the total rainfall in July more than 50 per cent above normal. The FEHD reminded the public to stay vigilant and keep up effective prevention and control measures against mosquitoes as the persistent rainy weather of summer would speed up mosquito breeding.

     "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 this year's first confirmed local DF case and another DF case with the source of infection under investigation in August, and four confirmed cases of Japanese encephalitis (JE) and one imported case of Zika Virus Infection so far this year, as well as reports of Zika Virus Infection cases continuing in neighbouring areas where DF has also remained highly prevalent, and that the hot and rainy weather of summer is favourable for massive proliferation of mosquitoes, the public should stay alert and work with the Government to continue to carry out effective mosquito prevention and control measures," an FEHD spokesman said.

     Among the 52 areas surveyed last month, the Area Ovitrap Index (AOI) in three areas reached or exceeded the alert level of 20 per cent. They were Lok Fu West (26.7 per cent), Tin Hau (26.5 per cent) and Yuen Kong (24 per cent).

     The spokesman said the FEHD has been very concerned about mosquito infestation. In view of the recent DF and JE cases, the FEHD has carried out targeted mosquito preventive and control work, including stepping up mosquito prevention and control work, and conducting entomological surveys in the vicinity of the residences and activity areas of the patients, as well as collecting samples of the vector mosquito for virus testing. Moreover, the FEHD has also liaised with relevant government departments and organisations to step up anti-mosquito measures in areas under their management. Furthermore, an inter-departmental anti-mosquito response mechanism has been activated in the above-mentioned areas with relatively high AOIs 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 to step up inspections of construction sites and enforcement action against mosquito breeding. In 2017 (as of August 11), the FEHD has instituted 152 prosecutions for mosquito breeding found on relevant premises under the Public Health and Municipal Services Ordinance (Cap 132), comprising 140 cases involving construction sites and 12 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," the spokesman said.

     As for the port areas, the monthly ovitrap index for Aedes albopictus for July also rose to 2.5 per cent from 1.8 per cent in June.

     "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 to remind the public to stay alert against the potential risks of mosquito-borne diseases, including DF, JE and Zika Virus Infection. The third phase of the territory-wide Anti-mosquito Campaign, lasting for 10 weeks, commenced on August 14. During the period, mosquito prevention and control work is being enhanced by the FEHD and relevant government departments. The district offices of the FEHD have targeted 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 intensified 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," he added.
     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 efforts 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 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 activity 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 of different areas and information on anti-mosquito measures are available on the department website at www.fehd.gov.hk.

Ends/Friday, August 25, 2017
Issued at HKT 18:30