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  Channel NewsAsia 5 Apr 07
Coming hot season threatens outbreak of type two dengue

Today Online 6 Apr 07
A deadlier dengue lurks Den-2 strain may take over as dominant virus: NEA
Nazry Bahrawi

Mosquito-breeding season is back, with a possibly deadlier sting.

As the National Environment Agency (NEA) warns of a possible dengue outbreak, one of its worries is that a switch in the strain of virus could escalate its spread.

Said its head of operations Tai Ji Choong: "From a random sampling of dengue cases, we have noticed more people being infected with the Den-2 virus this year, compared to the last three years, suggesting a possible change in the predominant virus strain."

This shift may lead to an increase of dengue cases here, he added, because fewer people will be immune to this new strain. Past trends will affirm this.

When there was a switch from the Den-2 to the Den-1 strain during the dengue outbreak in 2005, Singapore recorded 14,209 dengue cases — a jump of more than 30 per cent, compared to that of the previous year.

The NEA also said warmer temperatures could aid the spread of dengue. Temperatures are expected to hit 28°C and higher between April and September, an increase of 1°C over the January-to-March period.

This condition will enable the female Aedes mosquito — the carrier of the dengue virus — to mature faster, said the NEA. And this increases the chances of more Singaporeans being infected.

To prevent mosquito population build-up, the NEA yesterday announced it will step up efforts to remove potential breeding grounds and destroy mosquito larvae between mid-May and end-June in HDB and private estates at 44 dengue-prone areas across the island.

Residents at these locations tend to store more items at home, which, in turn, creates more mosquito-breeding spaces.

Said Mr Tai: "HDB estates are our primary targets … Cases that develop in housing estates have the potential to spread quickly, given the high density of people and numerous opportunities for the mosquitoes to breed and feed."

Last year, about 2,173 homes were fined for failing to comply with standards set by the NEA. In Singapore, it is an offence to breed mosquitoes. First-time offenders are fined $100, which goes up to $200 for subsequent offences.

The effort to check residential areas is part of a wider three-month Intensive Source Reduction Exercise (ISRE) that starts next week. About 500 NEA officers will make their rounds at common areas in 11,000 HDB blocks, and at condominiums and landed properties in Kembangan, Siglap, Mountbatten and other areas.

Meanwhile, an NEA survey of 1,200 respondents held last year shows that about half of those interviewed did not add sand granular insecticide to water or put insecticide in roof gutters, even though they are aware doing so could prevent mosquito-breeding. The agency plans to address this gap between awareness and action in its future outreach programmes.

Channel NewsAsia 5 Apr 07
Coming hot season threatens outbreak of type two dengue

SINGAPORE: The National Environment Agency (NEA) warns that the coming hot weather may bring about an outbreak of dengue.

Recently, 60 percent of the people who have caught the virus have been infected with type two dengue (Den 2) - a strain that Singaporeans have a lower immunity to.

Tai Ji Choong, Head, Operations, Environmental Health Department, National Environment Agency (NEA), said: "In the early part of this year, we are seeing more people infected with the Den 2 virus. So there could possibly be a shift in dengue sereotype.

"Whenever there is a change in dengue sereotype, there will usually be an increase in dengue cases. We urge the public to be even more vigilant this year."

The NEA explained that the severity of an outbreak would depend on several factors. These include rising temperatures which is what Singapore is experiencing now. More mosquito larvae will develop faster in hot weather so the dengue virus will also multiply at a higher rate.

Other factors that determine the nature of an outbreak are how virulent the virus is and the immunity of the population.

NEA will be carrying out its annual anti-dengue efforts over the next few months, against the backdrop of the rise in Den 2.

From next week, commons areas like perimeter drains, voids decks and roof tops in thousands of HDB blocks and private homes will be checked for mosquito breeding. The effort stretches to 44 areas around Singapore that are likely to report dengue outbreaks.

Together with past efforts and ad-campaigns, NEA said such exercises have seen some measure of success. According to its survey of 1,200 people conducted last year, nine out of ten carried out a quarter of the recommended actions.

And 80 percent of the respondents associated mosquitoes and mosquito breeding with stagnant water. But only half of respondents took all the five steps that NEA advised to guard against dengue.

Dr Pang Fung Yin, Head, 3P Partnerships, National Environment Agency, said: "We did ask the respondents why they were not translating knowledge into action. They said it was difficult because following the steps would take a lot of effort. We need to highlight to them that it is all worthwhile."

And that message could not have come sooner because this year's hot season is expected to peak from June to August with average temperatures hitting around 28 degrees Celsius. - CNA/so
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