NSW measles warning after five people diagnosed with dangerous disease

NSW Health is urging people to be alert for measles symptoms after five people who hadn't travelled outside Sydney were diagnosed with the serious disease.

All five sufferers first developed symptoms between Christmas and New Year's Day with NSW Health warning that other people may be infected.

Those diagnosed with measles had visited a number of locations across Sydney from December 26 to January 2 including Little Bay beach, Hyde Park, Maroubra, Macquarie Fields and Bankstown.

Acting communicable diseases director Christine Selvey says early measles symptoms include a fever, sore red eyes, a runny nose and coughing.

"Three or four days later, the characteristic red, blotchy rash appears," Dr Selvey said in a statement on Saturday.

"This starts on the face and neck and then spreads to the chest and the rest of the body."

Dr Selvey said measles was entirely preventable by immunisation, and anyone born during or after 1966 should ensure they had received two vaccines.

Those who may have been exposed by being in the same place at the same time are at risk of developing measles until January 20 as it can take up to 18 days for symptoms to develop.