Transcript of Oral Reply by Dr Vivian Balakrishnan, Minister for the Environment and Water Resources, to Parliamentary Questions on Dengue Prevention

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Date Published: 04 Aug 2014

Question by Ms Sylvia Lim: 

         To ask the Minister for the Environment and Water Resources (a) what steps, if any, are being taken to make the Sanofi dengue vaccine available in Singapore as soon as possible; (b) what timelines have been set for assessing the applicability to Singapore of controlling the mosquito population by infecting the male Aedes mosquitoes with the Wolbachia bacteria; and (c) what other methods are available in the pipeline and what resources are being committed by the Ministry to evaluating these other methods as counter-dengue measures.

Question by Mr Zaqy Mohamad: 

         To ask the Minister for the Environment and Water Resources (a) what is the cause of the record number of dengue cases in recent months; (b) what are the reasons for the spike despite many efforts in public education and regular checks by NEA; (c) whether NEA's measures and industry practices are still relevant to combating dengue; (d) whether the Ministry will consider heftier fines and more severe action for dengue-breeding culprits such as construction companies that pose a high risk of causing dengue outbreaks to large populations, including the reimbursement of medical bills for citizens affected by the outbreak that they cause.

Question by Mr Baey Yam Keng: 

To ask the Minister for the Environment and Water Resources whether the penalties for mosquito breeding can correspond to the size and scale of the breeding ground found, whether in households, public areas, construction sites or other areas.

Reply by Dr Vivian Balakrishnan:

         There have been more than 12,000 reported dengue cases so far this year. This dengue epidemic which has been ongoing since 2013 is driven by three factors. First, we experienced a switch in the predominant dengue serotype to DENV-1 last year. This strain of DENV-1 virus spreads more rapidly than the other strains in Singapore and in fact now accounts for about 90 per cent of all current infections. This is a historic high. The second factor is that our population in general lacks immunity to dengue infection, and this is a paradoxical result of our previous success and a cumulatively low incidence of dengue in the past, which means, by definition, most of us would not have had prior exposure and therefore lack immunity. Third, the mosquito Aedes aegypti is still endemic in Singapore in spite of our efforts over the past decades.

2.      The dengue risk is amplified during the current hot season, and that is because in times when there is hot weather, the maturation cycle of the mosquito accelerates and there is also a shorter incubation period of the dengue virus within the mosquito itself. Data from the National Environment Agency’s (NEA)'s 3,000 gravitraps which we have deployed island-wide has also shown a doubling in the population of adult Aedes aegypti mosquitoes since May 2014.

3.      ​Consequently, source eradication, or the elimination of mosquito breeding, remains our primary strategy. This year alone, NEA has conducted more than 1.9 million house or premise inspections and deployed more than 1,000 gravitraps in dengue clusters for mosquito-control purposes, in addition to the usual regular fogging and space-spraying in certain hotspots.

4.      As Mr Zaqy Mohamad has noted, poor housekeeping at construction sites pose a dengue risk to both their own workers onsite as well as residents in sites adjacent to the construction site. NEA has therefore increased inspections and taken stringent enforcement action against errant contractors whose sites breed mosquitoes. 62 Stop Work Orders have been issued this year alone; 14 contractors have been prosecuted in Court and they are liable for a maximum fine of $20,000 for the first conviction. Penalties have also been levied on homeowners, Town Councils and other landowners whenever breeding is found within the premises for which they are responsible. The fines levied this year have ranged from $200 for home owners and all the way to $39,000 for construction contractors. We will study the suggestion, which some members have put up, for us to increase penalties further.

5.      However, all Singaporeans must continue to stay vigilant and we must keep their homes free of breeding habitats. We have found more than 4,000 breeding habitats in residential premises this year alone, in the first seven months, and this shows that there is, frankly, still quite a lot more that we can all do to reduce the risk to our own families and to our neighbours.

6.      NEA’s Environmental Health Institute (EHI) is also working closely with international and local researchers to develop and evaluate new tools and strategies to deal with dengue. One interesting proposal which we are studying right now utilises the Wolbachia bacteria. When a male mosquito infected with Wolbachia bacteria mates with a female mosquito, no viable progeny is produced. Hence we are currently studying the feasibility of using such Wolbachia-infected male Aedes aegypti mosquitoes in order to suppress the overall population of mosquitoes in Singapore. I have appointed a Dengue Expert Advisory Panel, which consists of both international and local experts, to provide scientific advice to us on the safety and effectiveness of this technique in our local context. But as this is a novel biological intervention, I want to give you the assurance that we will not embark on field trials unless it is very clear that safety can be totally assured.

7.       NEA also works closely with the Health Sciences Authority (HSA) to monitor the development of dengue vaccines. I think there has been some publicity on this recently. In fact, according to media reports, Sanofi, which is a pharmaceutical firm, has been conducting Phase III clinical trials in Southeast Asia. HSA will review the Sanofi vaccine with the appropriate experts when Sanofi applies for approval to market the vaccines later on. Once the vaccine has been approved and registered, it will then become available through medical clinics and hospitals. However, I also want to caveat this point, that we will not approve vaccines unless we are sure it is safe and effective.

8.      I want to end by saying that our NEA officers – and every day there are about 850 of them going round homes – they have been working very hard on the ground to create a safe environment for Singaporeans. I want to thank all the NEA officers and I urge everyone here, and outside this chamber, to support the officers and to do whatever they can and whatever we can, in order to protect ourselves and our loved ones from dengue.

(Note: This is an interim transcript done by the Ministry. The transcript will be cross-checked with Parliament’s Hansard when it is ready and any necessary amendments will be updated then.)
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