Advisory Council on Food and Environmental Hygiene

Anti-mosquito Campaign and Enhanced Vector Surveillance in 2003

PURPOSE

This paper briefs Members on the 2003 Anti-mosquito Campaign and an enhanced vector surveillance programme implemented by the Food and Environmental Hygiene Department (FEHD).

Background

2. Mosquitoes can cause annoyance and serious problems in our daily life if there are no proper prevention and control measures in place. Some species of mosquitoes are capable of transmitting diseases like dengue fever, malaria and yellow fever, thus posing threats to human health. Sustained and concerted efforts from all sectors of the community are necessary to contain the harm and nuisance that mosquitoes can bring about.

Anti-mosquito Campaign 2003

3. Since 2001, annual anti-mosquito campaigns have been organised under the stewardship of FEHD to actively engage the community and government departments concerned in reducing the risk of mosquito-borne diseases notably dengue fever1. Control measures and publicity efforts are stepped up during the campaign period, supplementing the regular inspection and enforcement works carried out by district pest control staff. To sustain governmental and community efforts to prevent the spread of dengue fever, we have launched a new round of anti-mosquito campaign in 2003.

4. The Anti-mosquito Campaign 2003 features three phases, each lasting 6 weeks under a general theme of "Beware of dengue fever. Act now." Phase-specific slogans are set to heighten community awareness as follows:

Phase 1: from 24.2.2003 to 5.4.2003 under the theme of "Get prepared! Prevent dengue fever."

Phase 2: from 26.5.2003 to 5.7.2003 under the theme of "Eliminate stagnant water! Halt mosquito breeding."

Phase 3: from 25.8.2003 to 4.10.2003 under the theme of "Sustain our effort! Uproot mosquito problems"

5. During this territory-wide campaign, special attention is paid to areas favourable for mosquito harbourage and those in close proximity to human residence or vulnerable to introduction of dengue vector from other areas. Intensive anti-mosquito efforts are made at vacant government land, illegal cultivation sites, schools, construction sites, public housing estates, hospitals, waterfront cargo working areas, typhoon shelters, etc.

6. Like previous campaigns, the 2003 Campaign seeks to maximize its impact through the collaborated efforts of relevant government departments and public organisations. Members of the Inter-departmental Working Group on Pest Prevention and Control including the Department of Health, the Environmental Protection Department, the Housing Department, the Leisure and Cultural Services Department, the Agriculture, Fisheries and Conservation Department, the Marine Department, the Architectural Services Department, the Highways Department, the Social Welfare Department, the Labour Department, the Hospital Authority, the Education and Manpower Bureau, the Lands Department and the Home Affairs Department are monitoring and eliminating mosquito problems in sites and venues under their charge. They are also disseminating anti-mosquito messages and soliciting community support for the campaign through their networks.

7. On the public education front, we will be organizing a series of publicity and health education activities including roving exhibitions at major housing estates, theme exhibitions at FEHD's Health Education Exhibition and Resource Centre, health talks for students, social service institutions, construction sites management and workers, etc. Through Announcement of Public Interests (API) on radio and television, posters, pamphlets, banners, FEHD's homepage and hotline, the public will be reminded of the importance of elimination of mosquito breeding places and precautions against dengue fever. A variety of anti-mosquito activities will be organized under the auspices of District Councils and Clean Hong Kong District Promotion Committees to encourage community participation at district level.

Enhanced Dengue Vector Surveillance

8. Since 2000, FEHD has put in place a dengue vector surveillance programme by placing ovitraps at selected locations to detect the presence of Aedes albopictus in the territory. The surveillance programme not only furnishes information on the distribution of Aedine mosquitoes in the surveyed areas but also reflects the effectiveness of mosquito prevention and control efforts made by various parties. The data obtained is essential for timely adjustment of mosquito control strategy and measures.

9. In view of the spate of local dengue fever cases detected last year, FEHD has decided to launch an enhanced vector surveillance programme which features (i) a more systematic and comprehensive ovitrap survey and (ii) a pilot ovitrap study to gauge indoor mosquito breeding situations.

10. To enable members of the public to learn about the situation of mosquito problems at different areas and at different times of the year, FEHD has started publicizing 38 Area Ovitrap Indices (AOI) and a Monthly Ovitrap Index (MOI) on a monthly basis with effect from end February 2003. AOIs indicate the extensiveness of distribution of Aedes albopictus in the 38 surveyed locations while MOI is the average of all AOIs for a particular month, reflecting the territory-wide vectorial situation. The 38 locations, covering all 18 districts, include areas with high level of human activities (e.g. housing estates, hospitals, schools), areas surrounding the residence and workplaces of patients of previously reported local dengue fever cases, and other high-risk areas (e.g. waterfront cargo working areas, typhoon shelters). Around 50 ovitraps are placed in each surveyed location. The AOIs and MOI are announced through FEHD's website and press release every month. Maps at Annex I showing the distribution of the 38 surveyed locations have been posted on FEHD's website. Members of the Inter-departmental Working Group on Pest Prevention and Control are kept informed of the surveillance results so that timely and appropriate control actions can be taken to contain mosquito problems in sites/venues under their purview.

11. To facilitate the conduct of proper mosquito control operations and to enable the public to better comprehend the extensiveness of mosquito problems, we have classified the ovitrap indices into four categories:

Classification     Ovitrap Index (OI)
I OI < 5%
II 5% <= OI < 20%
III 20% <= OI < 40%
IV 40% <= OI

12. Anti-mosquito efforts will be made by relevant government departments commensurate with the OI level. When higher levels of OI are recorded, educational and publicity efforts will be stepped up and assistance from district organizations such as District Councils and Area Committees will be sought to mobilize more community resources to control the mosquito problems.

13. Ovitraps have hitherto been placed at ground level only, providing no information on the severity of mosquito breeding at higher levels and inside flats. In mid 2003, we will pilot an ovitrap study covering about 20 high-rise residential blocks throughout the territory. Ovitraps will be placed inside flats at different floor levels of the blocks. The findings of this pilot study will shed light on how best to prevent mosquito bites inside homes. The study will also indicate whether Aedes aegypti, the most important vector for transmitting dengue fever worldwide that prefers to breed in indoor containers, has been introduced into Hong Kong.

Anti-mosquito Steering Committee

14. The Anti-mosquito Campaign 2003 and the enhanced vector surveillance programme as detailed in paragraphs 3-13 were endorsed at a recent meeting of the Anti-Mosquito Steering Committee as part of a comprehensive package of anti-mosquito measures to be taken for the coming spring and summer. Annex II sets out the major achievements made by various bureaux/departments in winter and highlights their operational plans for the coming wet season.

Conclusion

15. Community involvement is a major pillar of the Administration's mosquito control strategy. The full benefits of the governmental actions outlined above cannot be achieved unless there are concerted efforts from the community. We need the partnership, support and assistance of every sector of the community to minimise the risk of mosquito-borne diseases in Hong Kong.

Health, Welfare and Food Bureau
Food and Environmental Hygiene Department
March 2003



1 Dengue fever is a severe viral illness transmitted by the bite of infective mosquitoes. Its symptoms include high fever, headache, rash, joint and muscular pain. It has re-emerged as a global threat in the past 30 years and has affected 2.5 billion people in over 100 countries. Hong Kong is under the constant threat of dengue fever as it is an endemic disease in our neighbouring regions including Southeast Asia, South Asia and the Pacific area.

 

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