Public Health. Highly urbanised and a food paradise, Singapore is vigilant against vector-borne and food-borne diseases. chapter4: p45 PUBLIC HEALTH

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2 chapter4: p45 TOWARDS ENVIRONMENTAL SUSTAINABILITY State of the Environment 2005 Report chapter 04 Public Health Highly urbanised and a food paradise, Singapore is vigilant against vector-borne and food-borne diseases. PUBLIC HEALTH VECTOR CONTROL Public health involves a kaleidoscope of issues and comes under the purview of several government agencies working in concert with each other. Among these, the National Environment Agency (NEA) is the government agency responsible for vector control and food hygiene. Vectors are animals that carry disease that can infect humans. Examples of vector-borne diseases are dengue fever, malaria, typhus and bubonic plague. Their very names strike fear in people s hearts because they can cause immense suffering and loss of life. Thanks to Singapore s clean environment, many vector-borne diseases commonly found in tropical countries are rare here. However, we must continue to keep a constant guard against vectors for two major reasons: Given the right conditions, some vectors (for instance Aedes mosquitoes and rats) thrive in an urban environment; Singapore has one of the world s highest population densities; any outbreak of vector-borne disease has the potential to spread very rapidly. Country Population/sq km Macau 24,111 Hong Kong 6,366 Singapore 6,300 India 300 United Kingdom 242 Source: 2001 UK Census on Population Densities

3 Photo by courtesy of Northwest Community Development Council Mosquito-borne diseases Despite Singapore s location in the malaria-endemic tropics, we are malaria-free. The majority of malaria cases (98.7%) reported here are imported, i.e. contracted overseas. One problem that we have, however, is dengue fever/ dengue haemorrhagic fever. The main vector-borne disease in Singapore, it is transmitted by Aedes mosquitoes which breed in clean, stagnant water commonly found in man-made containers in urban environments such as flower pots. The presence of these conducive breeding grounds and increased urbanisation contribute to an increase in this disease. The low-down on dengue Dengue fever and dengue haemorrhagic fever are caused by one of four virus serotypes (DEN-1, DEN-2, DEN-3, and DEN- 4), of the genus Flavivirus. Infection with one serotype does not make a person immune to infection from the other serotypes. Primarily a tropical disease, dengue is spread mainly by Aedes aegypti, a day-biting mosquito that prefers to feed on human blood.

4 chapter4: p47 This year, several countries have reported an increase in dengue cases from the previous year. Singapore too, saw a doubling in the number of cases compared to No. of Cases Dengue Fever/Dengue Haemorrhagic Fever 4,788 9,459 Malaria Local 5 2 Imported Japanese Encephalitis 0 0 Dengue fever is transmitted by the Aedes mosquito Rodent-borne diseases Rats are another vector that thrives in an urban environment. This is because humans often create favourable conditions for them, for example by indiscriminately littering food wastes. Local rodent species in Singapore are the Norway rat (Rattus norvegicus) and roof rat (Rattus rattus diardii). Rats have the potential to spread several diseases, including rat bite fever, salmonellosis and leptospirosis. They can also host rat fleas that transmit plague. In the interest of public health, rodent population has to be kept low through effective rodent control by denying them food and nesting places. Therefore, great emphasis is placed on environmental sanitation and hygiene in Singapore. A pest control operator spraying rat poison into a rat burrow

5 A PROACTIVE APPROACH While the ability to react quickly to outbreaks is vital, NEA takes a proactive approach that goes well beyond this. It has a far-reaching programme to: wide-ranging research, enlisting the help of the community, and engaging professional bodies to design and build mosquito-proof or maintenance-free structures to prevent mosquito breeding these are all part and parcel of NEA s efforts. reduce vectors such as mosquitoes and rodents; detect existing and emerging diseases carried by vectors; prevent vector breeding. Meticulously monitoring the ground situation, conducting Ground control NEA s vector control operations teams operate from its five Environmental Regional Offices to conduct routine inspections, preventive surveillance and education in dengue-sensitive neighbourhoods. Wherever outbreaks occur, additional teams are deployed to contain the outbreak quickly. 5 Regional Office Locations North West Regional Office North East Regional Office South East Regional Office Central Regional Office South West Regional Office

6 chapter4: p49 Command and conquer While our field officers are familiar with the ground situation, certain trends and irregularities can be identified only after surveillance data are analysed. This important function is fulfilled by a command centre. There, using the Geographical Information System, our vector control specialists process information on the locations of vector populations and the incidences of vector-borne diseases. Using a graphical interface, they monitor the development and movement of hotspots with high mosquito breeding or dengue fever cases. Such information is then communicated to the ground operations teams so that they can zoom in quickly to tackle the problem before it grows out of control. Use of GIS in vector control operations Field officer enters survey data into PDA Laboratory officers identify & enter vector species Data in server Vector breeding details plotted in GIS Spatial-temporal analysis by Situation Room Early warning of hotspots. Deployment of operational staff to hotspots

7 Know the enemy Important as work on the ground is, it needs to be supported by upstream research. To this end, the Environmental Health Institute (EHI) was formed in Through its own research and partnering with other institutions, the EHI aims to develop disease prevention and control measures that are cost-effective. Through its own research and partnering with other institutions, the EHI aims to develop disease prevention and control measures that are cost-effective. EHI research areas Vector Support and Research Assessment of vector control tools, including pesticides Reference Laboratory for Vectors of Singapore Development of new tools for vector control and monitoring Investigation of vector genetics, behaviour and distribution Study of mosquito-virus interactions Surveillance of vectors for other diseases like West Nile and Hanta Viruses. Molecular Microbiology Development of tools for rapid and early diagnostics and epidemiology of Singapore Monitoring of dengue virus dynamics Development of Dengue Reference Collection in Singapore Indoor Air Quality and Legionella Study on Legionella virulence Risk assessment of indoor air quality Investigation of new parameters for indoor air quality The role of the EHI is to investigate and research infectious diseases whose transmission is governed mainly by environmental factors. Besides developing tools for vector control and diagnostics, the EHI seeks to understand the epidemiology of endemic vector-borne diseases such as dengue. This involves assessing patterns of disease with respect to environmental factors. Surveillance and research of diseases that threaten Singapore also prepares us to detect emerging diseases. In the event of an actual outbreak, the EHI would provide information on the vectors involved, as well as identify and screen vector and virus samples.

8 chapter4: p51 The Gravitrap The Gravitrap is one of several patents the EHI has filed since its inception. It is so called because it traps female mosquitoes that are gravid, i.e. ready to lay eggs. This is an improved version of the ovitrap which kills only the offspring but does not capture the gravid female mosquitoes. In order for the Gravitrap to help reduce mosquito populations, thus contributing to reduced dengue transmission, it needs to be deployed in large numbers over vast areas to compete with other breeding sites. An initial field trial is planned with 10,000 pieces of the Gravitrap. Advantages of the Gravitrap are that it: Captures the egg-laying females as well as their offspring Requires minimal maintenance (non-reliant on moving structural parts) Will not turn into a breeding source with neglect (foolproof) Is user-friendly Can be mass-produced Is relatively cheap Is disposable Community warriors Over the years, NEA has embarked on a series of programmes to raise public awareness and mobilise our community to help reduce the vector population. As part of this relentless effort, two pilot programmes were launched in Mozzie Attack aims to rally the public to eliminate stagnant water and household objects that hold stagnant water, as these are good breeding habitats for Aedes mosquitoes. Volunteers organised exhibitions, door-to-door visits and talks to get the message across to residents 1. Rat Attack declared war on rats. It demonstrates effective ways to reduce rodent infestation in residential neighbourhoods, and emphasises the need for total community involvement to sustain rodent control 2. NEA intends to roll out these programmes to all neighbourhoods in Singapore eventually. A volunteer checking for mosquito breeding 1 For more on Mozzie Attack, see Chapter 5. 2 For more on Rat Attack, see Chapter 5.

9 FOOD HYGIENE Besides her reputation for cleanliness, Singapore is also renowned as a food paradise. Dishing up a spectacular variety of cuisines are a staggering 16,000 dining establishments, ranging from fine restaurants to humble hawker stalls. Every one of these dining establishments is closely monitored for hygiene by NEA. Because of this high standard of food hygiene, Singapore generally has a low incidence of food-borne diseases. Germ warfare Because of this high standard of food hygiene, Singapore generally has a low incidence of food-borne diseases. This is particularly reassuring in a country where eating out is an intrinsic part of the local lifestyle and tourist experience alike. Besides stringent licensing, inspection and enforcement, NEA employs several other measures to encourage good food hygiene practices at food outlets.

10 chapter4: p53 Grade expectations All eating establishments and foodstalls are graded on their housekeeping, cleanliness, pest infestation, food hygiene and personal hygiene of its food handlers. (The grade has no bearing on the taste of the food). Displaying the grade for each food outlet lets customers make informed choices. Grade Year A (Excellent) B (Good) C (Average) D (Poor) Foodshops % Foodstalls in private eating establishments % Foodstalls in government hawker centres % % 49.39% 20.63% 0.31% % 47.48% 9.95% 0.08% % 33.37% 64.01% 0.11% % 42.91% 41.68% 0.01% % 38.61% 59.52% 0.73% % 45.70% 43.70% 0.45% In addition, a Straight A s Programme has been implemented to enhance food hygiene standards at school cafeterias and air-conditioned foodcourts. A major component in this programme is a self-check system for stall operators to track their own performance. With inputs from NEA, foodcourt managers also carry out regular audits and reviews.

11 Adam Road hawker centre after upgrading Upgrades available Hawker centres 3 are bastions of good local food, immensely popular with Singaporeans from all walks of life. The Hawker Centres Upgrading Programme is an ambitious 10-year scheme to give major facelifts to 110 of these hawker centres, while retaining their unique charm and Singaporean identity. Adam Road hawker centre before upgrading The Hawker Centres Upgrading Programme is an ambitious 10-year scheme to give major facelifts to 110 of these hawker centres. The upgrading works are not merely cosmetic. They include re-tiling, enlarging the stalls, improving the toilets and refuse bin centres, as well as overhauling the ventilation, electrical, exhaust and plumbing systems. The result: premises that are cleaner, brighter, airier and more easily maintained. Patrons can thus look forward to tucking in amid more pleasant surroundings and higher standards of hygiene. Upgraded toilet at Dunman food centre The total cost of the programme is expected to be S$420 million. To date, 34 centres have been upgraded, and patrons have reacted with enthusiasm. 3 For an explanation of hawker centres, see page 6.

12 chapter4: p55 CHALLENGES Singapore has been able to maintain a low or zero incidence of most food-borne and vector-borne diseases. Singapore has been able to maintain a low or zero incidence of most food-borne and vector-borne diseases. It is an extremely safe place for residents, tourists and business investors. But such diseases are opportunistic and our community cannot afford to let up on efforts to prevent them. The flow of different dengue virus strains among countries in endemic zones will continue to be a challenge to Singapore, which is situated in the midst of an endemic region. We also need to be vigilant against emerging diseases. These could include West Nile Virus, Nipah virus, Yellow Fever and Japanese Encephalitis. NEA will continue its surveillance and research programmes in these areas. We have laid a foundation in prevention measures, early warning systems and research. But the challenges ahead underscore the need for us to improve further in these areas, so that we always remain one step ahead of diseases.