More than 372,000 inspections were carried out by the National Environment Agency (NEA) in the first five months of this year to check on mosquito breeding across the country amid a surge in dengue cases.
Of these, about 6,500 instances of mosquito breeding habitats were found, NEA said in a statement yesterday.
NEA also fined around 900 households for breeding mosquitoes.
The two largest clusters for dengue - the deadly disease carried by the Aedes mosquito - are both in Woodlands, including Woodlands Avenue 6, Woodlands Circle, Woodlands Crescent and Woodlands Ring Road. Together they accounted for 360 cases.
Other large clusters were found in Geylang, including Guillemard Road and Sims Avenue (115 cases); Chai Chee (112 cases); and the Thomson area, including Jalan Lembah Thomson, Soo Chow Rise and Upper Thomson Road near Lakeview (99 cases).
In these areas, 74 per cent of the breeding occurred in homes, which is much higher than the national average of 60 per cent.
These official figures come at a time of an islandwide surge in dengue cases.
As of 3pm on Friday, there had been 5,534 dengue cases this year, about four times the figure in the same period last year.
For the week ending on the same date, there were 467 cases of dengue fever - the highest weekly number since March 2016.
Five people have died from dengue so far this year. The latest victim, an 84-year-old woman who lived in Geylang Lorong 6 - one of the largest active dengue clusters - died on June 14.
While the five clusters have accounted for the bulk of the increase in dengue cases, there has been a "general uptrend" across Singapore, the statement said.
"The dengue transmission is therefore not localised, and everyone has to be alert to the threat," it added.
NEA warned that with the warmer months from June to October, a national collective effort is critical to prevent dengue cases from rising further.
"All residents living in cluster areas are strongly encouraged to cooperate with NEA officers, and facilitate their checks and indoor misting in their homes," NEA said.
The Straits Times reported last Thursday that between 2017 and last month, at least 175 households were served legal notices for failing to allow NEA officers into their homes for dengue-related inspections.