Fourth measles case in NSW in one week

NSW Health has issued a fresh measles warning after a woman in her 40s became the latest person in the state to be diagnosed with the disease.

It's believed the woman contracted the disease in mid-March while visiting the Eastwood shopping precinct in Sydney's northwest.

She spent time in several areas between March 28 and April 4 including Crows Nest and Eastwood while infectious.

NSW Health is urging people who may be susceptible to measles and who may have been in the same locations to be alert for symptoms of measles until April 22.

Thirty-one people have now been diagnosed with the highly contagious disease in NSW since Christmas Day to 31.

Earlier this week, two babies too young to be vaccinated were confirmed to have caught the disease in Sydney.

Authorities on Thursday also confirmed a different young woman had been diagnosed with the disease and was likely to have been exposed to the highly contagious disease in a GP waiting room.