NSW adults urged to check measles records

People aged 20 to 50 are being urged to check their vaccination history as the number of measles cases in western Sydney continues to climb.

The latest patient, who was under-vaccinated, brings the total number of confirmed cases in the current outbreak to 17 and this year's total to 23.

That person spent time at Sydney's Powerhouse Museum, Darling Harbour, Liverpool Westfield, Blacktown Hospital and Casula Central Medical Practice, and a nearby Chemist Warehouse between April 13 and 18.

NSW Health spokeswoman Dr Vicky Sheppeard said some people born between 1966 and 1994 might have had only one dose of the measles vaccine instead of the required two because of vaccination scheduling changes.

"Don't assume you are covered unless you have written records of two doses," she said in a statement on Friday.

"It is perfectly safe to have the measles vaccine again if you are not sure whether you've had two doses of the vaccination in the past."

The vaccine is free to people in that age bracket through a GP, she said.

Sydney's western suburbs have some of the lowest rates of immunisation in Australia.