A Malaysian woman is believed to be the first patient infected by locally-transmitted Zika virus in Singapore.

The Singapore Ministry of Health (MOH) and National Environment Agency (NEA), which have been informed of the Zika virus infection, said as the 47-year-old had not travelled to Zika-affected areas recently, she was likely to have been infected in the republic.

She resides at Block 102, Aljunied Crescent and works in Singapore.

"MOH and NEA are working together to carry out vector control and testing of residents in that area with fever and rashes, so as to reduce the risk of further spread," said Health Minister Gan Kim Yong in a statement today.

"I encourage those who are unwell and with such symptoms to visit the doctor for medical attention. We have also alerted our clinics in the area to look out for suspect cases and refer them to the Communicable Diseases Centre (CDC) for testing."

According to MOH and NEA, the patient had developed fever, rash and conjunctivitis from Aug 25.

She visited a general practitioner (GP) on Aug 26 and was referred to the CDC at Tan Tock Seng Hospital where she tested positive for Zika on Aug 27.

She has since been hospitalised for observation at the CDC and is currently well and recovering.

MOH and NEA said with the presence of Zika in the region and the volume of travel by Singaporeans as well as tourists, it was inevitable there would be imported cases of Zika into Singapore.

There is also risk of subsequent local transmission, as the Aedes mosquito vector is present here.

While MOH and NEA have stepped up precautionary measures, it was expected there might be further cases, as most infected persons might display mild or no symptom, said the statement.

MOH is screening the patient's close contacts, including household members and carrying out Zika testing on others living and working in the area, displaying symptoms of fever and rash.

At this point, three other suspect cases – two in a family who live in the area and an individual who works in the area – had preliminarily tested positive based on their urine samples.

They are pending further confirmation tests, said the statement.

For now, as an added precaution, all suspect cases of Zika virus infection would be isolated while awaiting confirmation of the blood test results, said the statement.