Two locally transmitted cases of the Zika virus have been confirmed in Simon Place, near Kovan in Hougang. Both are from the same household.
The Health Ministry yesterday declined to reveal details of the two, but The Straits Times understands that neither person is pregnant.
The cluster is the first reported this year. There have been six other isolated cases this year. A cluster is formed when at least two cases occur within 14 days and are located within 150m of each other.
Residents have been urged to remain vigilant in detecting mosquito breeding spots, as most people infected with Zika do not develop symptoms, so it may take some time before the virus is detected.
Zika is transmitted by the Aedes aegypti mosquito, which also carries diseases such as dengue and chikungunya.
Singapore's first locally transmitted case was detected in August last year, while the last cluster was closed in December last year. That cluster, in Bedok North Street 3, had seven cases.
The National Environment Agency (NEA) on Tuesday started vector control operations in Simon Place, as well as outreach activities.
As of yesterday, NEA has inspected about 120 out of some 400 premises in Simon Place for mosquito breeding, alongside ground checks in the vicinity.
Seven breeding habitats in homes and three on other premises were detected and destroyed.
Indoor spraying of insecticides, together with thermal fogging and misting at outdoor areas, has been carried out.
NEA officers and grassroots volunteers are distributing information leaflets and insect repellents to households to raise awareness of Zika. They also stress the need to prevent mosquito breeding.
Residents are asked to allow NEA officers to carry out inspections and indoor spraying of their homes.
Aljunied GRC MP Sylvia Lim said: "I thank NEA for its concerted work and urge residents to cooperate fully and to exercise personal vigilance."
Ms Lim added that she would be visiting some residents in the affected cluster today.
Members of the public are advised to seek medical attention if they are unwell, especially if they have symptoms such as fever and rash. They should also inform their doctors where they live and work.
By the end of last year, more than 450 people here had been diagnosed with the Zika virus.