SINGAPORE — As the number of dengue cases hit another weekly high of 567 cases last week, construction sites have also become a source of concern for the authorities.

As at May 10, the National Environment Agency (NEA) had found 159 dengue cases at construction sites — more than double the 71 cases detected for the whole of last year.

The number of mosquito breeding spots found at construction sites stands at 616 cases in the first four months of this year, comparable to the 670 cases in the corresponding period last year. In 2011, 584 breeding sites were found at construction sites.

While he noted that the majority — seven out of every 10 cases — of mosquito breeding sites are found in homes, NEA Director of General Public Health Derek Ho said “a concerted effort” among all stakeholders is required to beat back dengue.

He said: “Whether you’re a resident in your own home or whether you’re a stakeholder in the community for public areas, such as construction sites, we all need to maintain our vigilance.”

To control mosquitoes breeding at construction sites, the NEA requires contractors to submit an environmental control programme outlining preventive measures, such as appointing an environmental control officer, stipulating the frequency of checks for breeding spots and engaging a pest-control company to do regular fogging.

NEA officers will conduct monthly on-site checks and point out lapses to the contractor. In areas where there are reported cases of dengue transmission, these checks will be stepped up to twice a week.

“On top of that, if we assess the sites to be unkempt and not properly managed in accordance to what has been laid out, we will visit more frequently, even to the extent of visiting on a daily basis to ensure that they do what is necessary to improve housekeeping and so forth,” added Mr Ho.

Construction sites found to be breeding mosquitoes can be fined S$2,000 for the first offence.

For second and third offences, they can be fined S$4,000 and S$5,000 respectively. In the first three months of this year, 172 fines were issued to contractors as compared to 230 in the same period last year, said an NEA spokesperson.

Apart from construction sites, the NEA is also working closely with dormitory operators housing foreign workers to educate workers on the threat of dengue. The NEA has distributed pamphlets and brochures in the languages of the foreign worker communities and has encouraged the self-appointment of ambassadors to “help spread the word”.

Private developer City Developments, which has 14 sites under construction, is a developer which has had no dengue cases detected so far this year. It implements stringent health, safety and environment control measures in regulation with the NEA’s requirements and “a variety of hard and soft measures” to ensure compliance, said its Deputy General Manager for Projects Division, Mr Allen Ang.

These include handing out internal awards for maintaining a stipulated level of hygiene at work sites and imposing a financial penalty on contractors who have received fines or stop-work orders from the authorities.

According to the NEA’s website, there have been 105 reported dengue cases so far this week. The number of high-risk clusters — where there have been more than nine dengue cases — stand at 19 and include areas such as Tampines, Yishun and Bedok.

Based on projections, the NEA expects to enter the peak dengue season at about 700 weekly cases, even though the number of cases in recent weeks has hovered around “500-something”, said Mr Ho.

“It does seem that the cases are plateauing, but we would need more data points in the subsequent weeks to see how the situation develops,” he added. Woo Sian Boon