Residents, including school students in Eastwood and the surrounding area, are being urged to be alert for measles symptoms, after a woman became the 31st person in NSW to be infected with the disease since Christmas.

It's believed she was infected in mid-March while visiting Eastwood's shopping precinct, including Eastwood Shopping Centre (March 28th), the North Sydney Boys High School's uniform shop (March 28th), MyHealth Medical Centre (April 2nd) and the DHM Collection Centre on Rowe Street (April 2nd and 4th).

Outbreak: A woman in Sydney has become the 31st case of measles in NSW since Christmas.

NSW Health acting director of communicable diseases, Dr Sean Tobin, said none of the locations visited by the woman pose an ongoing risk - but said people should be wary if they were in those areas on the same days.

“They should also be alert for signs of measles until 22 April 2019, as it can take up to 18 days for symptoms to appear following exposure,” Dr Tobin said.