Sydney woman diagnosed with the measles

A health alert has been issued after a Sydney woman became the seventh person diagnosed with the measles in NSW this year.

NSW Health on Sunday said the woman spent time in Bondi Junction, Rose Bay and Double Bay while infectious from Australia Day on January 26 to January 31.

Deputy public health director Dr Vicky Sheppeard said infants, pregnant women and people with compromised immune systems who were at Bondi Junction 7-day Medical Centre between 10:30am and 11:30am on January 28 are urged to contact the public health unit to determine if protective antibodies are required.

It can take up to 18 days for symptoms to appear following exposure to someone with the infection.

Symptoms include a fever, cough, runny nose and sore red eyes, followed three to four days later by a red spotty rash, which starts on the head and spreads to the rest of the body.

"Anyone who develops symptoms of measles should phone their GP to ensure they don't wait alongside other patients before seeing their doctor," Dr Sheppeard said in a statement on Sunday.

Measles is highly contagious and is spread in the air by people who are infected who cough or sneeze.