THE culprits behind the dengue "mega cluster" in Serangoon and Hougang that has infected more than 500 people so far have been taken to task.
The National Environment Agency (NEA) has issued warnings and fines to residents, town councils and contractors in whose homes and areas mosquito breeding was found.
A nine-day Stop Work Order was also issued to Singapore Piling & Civil Engineering on June 2 after 10 breeding sites were found at its construction site in Simon Road, the agency said yesterday in response to queries from The Straits Times.
About 200 NEA officers have been fanning out every day to find mosquito breeding sites across the 17 conjoined clusters from Hougang Avenue 2 in the north to Bartley Road in the south, an area roughly the size of Sentosa.
More than 7,200 people have been infected with dengue so far this year, with one death. Last year's record dengue epidemic struck more than 22,000 people and seven died.
But with the arrival of the hotter months from June to October - the traditional peak season for dengue - the virus could spread faster as the insects breed more rapidly.
Block 161 Hougang Street 11, which is in the country's largest cluster with 144 infections, has alone had 15 infections.
Ms Kelly Ng, 42, an accounts assistant and resident of the block, said her daughter, 15, might have been infected with dengue last month at the nearby Paya Lebar Methodist Girls' Secondary School. Other residents The Straits Times spoke to suspected road-widening works in Upper Paya Lebar Road of harbouring mosquito larvae.
But the NEA said yesterday that neither the school nor the roadworks had any breeding grounds. In fact, homes made up 60 per cent of breeding sites found, it said. Areas maintained by town councils formed 21 per cent, while construction sites accounted for only 9 per cent.
During last year's epidemic, homes, too, made up the majority of breeding grounds, despite the public's impression that work sites were the major culprits.
The NEA reminded residents to play their part in preventing mosquitoes from breeding in stagnant water, which can collect in plant pot plates or containers at home.
It also advised them to use insect repellent when they go out.
Mr Vincent Leow, 57, a general manager who lives in Aroozoo Avenue in the biggest cluster, said he was taking no chances, especially with his six-year-old son.
The family now sleeps with the windows shut and air-conditioning on.
"Of course we're worried," he said, pointing out that the empty house next door could be a breeding ground. "We try to keep (the son) indoors nowadays."