Tackling Recent Rise in Dengue Cases

Mdm Speaker, over 11,200 dengue cases were reported in 2015, and this is lower than in 2013 and 2014. However, we should worry because in the recent few months, there have been a higher number of cases compared to corresponding periods in previous years. We expect the total number of dengue cases in 2016 to be high, with cases spiking earlier than usual. This increase may be due in part to the change in the main circulating dengue serotype. We have also observed an increase in the Aedes mosquito population. The warmer-than-usual year-end weather due to the El Nino phenomenon has aided the breeding and spread of both Aedes mosquitoes and the dengue virus in Singapore and in the region.

Source reduction remains the most effective way to curtail the transmission of dengue. In anticipation of a rise in dengue cases, the National Environment Agency (NEA), together with members of the Inter-Agency Dengue Task Force, has stepped up source reduction efforts earlier than usual. From November to December 2015, NEA conducted more than 193,000 inspections and removed more than 4,000 breeding habitats, the majority of which were found in homes, and this can be found in containers, flowerpots, the usual places. NEA has also stepped-up publicity efforts to raise awareness of the "Five-Step Mozzie Wipeout" and encourage the community to take part actively to prevent dengue.

Owners of premises in dengue clusters found with breeding habitats can be fined up to $5,000 under the Control of Vectors and Pesticides Act. Already more than 1,000 households in dengue clusters were fined in 2015. The current penalties have been effective in keeping re-offending rates low. Nonetheless, my Ministry will continue to monitor the situation and introduce stiffer penalties if necessary.

Besides checking homes, NEA has also intensified checks for other areas, including construction sites, and taken stern action against those found breeding mosquitoes. In 2015, more than 900 Notices to Attend Court were issued to construction site contractors and over 100 Court prosecutions were taken against contractors for repeat offences. In the same period, more than 100 Stop Work Orders have been issued to construction sites to ensure that proper mosquito control measures were put in place before construction was allowed to resume.

My Ministry has set aside about $2.5 million each year to conduct multidisciplinary research in controlling the mosquito population, for example, for the development of surveillance and control tools such as Gravitraps. In addition, more than $3 million has been committed over the next three years to develop a novel method of suppressing the Aedes mosquito population through the use of male Aedes mosquitoes that carry Wolbachia, a naturally occurring bacterium that can prevent mosquito eggs from hatching. The Government is also tracking the development of the dengue vaccine, Dengvaxia, and will carefully evaluate the vaccine to ensure that it is safe, of high quality and effective before it is made available in Singapore.

As a community, we need to continue to play our part to remove potential breeding habitats from places under our care. This is the most effective way to control mosquito breeding. My Ministry will also continue to work with our partners to keep up our fight against dengue through a combination of surveillance, public education, enforcement, source reduction, as well as research into new methods of mosquito reduction.

I thank the Minister for the comprehensive reply. With the reported outbreak of Zika, which is transmitted through mosquitos, may I know what are the measures that have been taken, and what other steps can the Ministry take to help Singaporeans and to prevent this disease from spreading in Singapore?

We are equally worried about the possible detection of Zika in Singapore. To facilitate this, the Ministry of Health (MOH) is working with NEA to enhance ongoing laboratory surveillance of sample Zika infection. Already, Zika is a notifiable disease under the Infectious Diseases Act. However, having said that, the Zika virus is also transmitted by the same type of mosquito that transmits dengue. Therefore, whatever we do for dengue, if we are effective, will also be effective to prevent Zika from spreading.

What we are working on is that in the event that Zika were to be found in Singapore, even a single imported Zika or a local Zika case, NEA will then start to step up its vector control activities around the case's residence and/or the workplace. If it were a single local case, we will also conduct a vector control in the case's contacts' residences. That is the first step.

But beyond that, I think it is important for all of us to play our part to understand about the dengue-spreading mosquito and the real impact of how we can reduce this threat; and to understand that, in just a week, an egg can hatch into an adult mosquito and, within three weeks, the same mosquito, if it is female, will start laying 300 eggs. That is how it starts to spread virulently. Therefore, we ask everybody to go out, help do something within your homes, stop its breeding, do the "Five-Step Mozzie Wipeout" and, if we are effective in this, we can also prevent Zika from spreading, if it should come to Singapore.

May I ask the Minister what is the new update on the new dengue vaccine? What was the outcome of the dengue vaccine which was on trial in Tan Tock Seng Hospital and whether there are now enough safety studies done for us to administer this vaccine more widely?

Unfortunately, this area is under MOH and I do not have the details to be able to answer the question. If the Member is keen to know the answer, the Member could file a Parliamentary Question on that to MOH.

I thank the Minister for the response earlier with regard to how we manage and control the spread of dengue on the ground. First and foremost, the Minister alluded to the fact that the majority of the cases are in the homes. I think the challenge is that in the residents' perception, most of the time, it comes from outside. So, what proportion, based on breeding sites, in any area has the Ministry found where dengue breeding is in the homes, compared to the external areas? That is the first question.

The Minister also mentioned that there is research being done to use male dengue mosquitos, for example, to control and curb this virulent spread. What safeguards are in place to ensure that when we do these biomedical, genetic modifications that they do not mutate to something else and cause other issues, even Zika?

The number of residential premises that we have discovered breeding is actually large. But on record the number of enforcements that we have carried out against residential premises is about equal to that of construction sites. That is because we give them a stern warning for the first instance of discovery. What we have found is that if we enforce against the recalcitrant – that means having found and given a warning, we still find it again, and we impose a penalty on them – then the recurrence of finding breading in that home disappears, almost disappears. Unfortunately, not everybody has taken a chance, but when given a penalty, that habit of checking on these things suddenly becomes much better.

On the Wolbachia, we have been looking at this since 2005. Our department has been looking at what we can do to suppress the population, first, of Aedes aegypti, particularly prevalent during warm weather. This Wolbachia-carrying Aedes aegypti is not a genetically modified (GM) organism. And this has been confirmed by the Genetic Modification Advisory Committee in Singapore. So, the Member can rest assured that it is not a GM-mosquito.

There are many ways to do this. But what we are trying to do is to use the male Aedes aegypti which will Wolbachia-carrying, to introduce that and compete with the wild-type males for the wild-type females. Because what the scientists have discovered is that when the eggs are laid, they do not hatch. Although promising, this is something we still need to study further, and to continue to look at what the field experience is like in other countries as they experiment on this, and to ensure that when we do this in Singapore, the impact on environment and health, and even how it affects other insects or population is not adverse.

Thank you, Madam. I have one supplementary question for the Minister concerning source eradication. We have some residents living in private estates who may be living adjacent or near to private land which is unoccupied. I would like to ask what is NEA's response in such matters; as in, how far does NEA go to follow up to do checks within such premises, whether with or without the owners' consent, and is it a check on 100% of such premises or is it based on complaints?

Part of our effort is to not just be reactive but to be proactive at the start or before the advent of the dengue season. So, like I mentioned just now, we have made a lot of inspections. Altogether, in 2015 alone, there were 1.4 million inspections around Singapore. In addition to the inspections, we put in what we call "Gravitraps" to monitor whether mosquitos are breeding in that area, to look at the density of the breeding, as well as the people who get infected, from their blood, to understand the serotype changes, be able to map and, therefore, to be able to look at what are the possible risks that can be prevented both to the areas as well as to the country.

Should that then appear to be something very risky, then we will deploy our resources to the appropriate places and make sure that the population comes together to make sure that they, too, will take the steps to make sure their homes are not breeding mosquitos.

For those homes which we could not get access into, we will put a notice on their doors because we do not know why they are not there. Maybe they are on holiday or for whatever reason. But within a week, if there is no response, particularly in this period, we will have enough powers to get access into the premises and do the necessary inspection and destruction of breeding, if it is found.