NSW Health said on Wednesday the baby - who is too young to have been vaccinated - was recently visited by extended family from an area where there's a current measles outbreak.

The baby was taken to Plumpton Marketplace food court on January 31 while infectious with NSW Health urging people there at the same time to look out for measles symptoms until February 17.

Western Sydney Local Health District director Dr Shopna Bag says people not immune to the highly contagious disease are at risk if they've been exposed to an infectious person.

"Anyone who develops symptoms should arrange to see their GP and call ahead to ensure they don't wait in the doctor's waiting room with other patients," Dr Bag said in a statement on Wednesday.

Symptoms include fever, coughing, runny nose and sore red eyes, followed by a red spotty rash that starts on the head and spreads down.

Australian Associated Press