South Australia has recorded an additional patient with measles, linked to a cluster of cases at Brighton Secondary School.
New exposure sites include the emergency department at the Queen Elizabeth Hospital, two pathology centres and a pharmacy.
SA Health urges anyone who may have been in contact with the infected person to monitor for symptoms.
Contact tracing is underway at a South Australian hospital after a confirmed case of measles spent more than 24 hours in the emergency department, among dozens of other newly-listed exposure sites.
SA Health said the latest case was a person in their forties linked to the cluster of cases at Brighton Secondary School.
Three students contracted the highly-infectious disease from an initial case who had returned from overseas and tested positive on September 14.
The latest infection brings the school cluster to five and the state's total to nine so far this year.
SA Chief Public Health Officer Nicola Spurrier said the latest patient had a known exposure to the first case and has been hospitalised in a stable condition.
According to the SA Health, the patient was in the Queen Elizabeth Hospital emergency department's waiting area on September 23 from 5:15pm for about five hours.
Then the person was at the emergency department's "fast-track" area — which SA Health said was for patients who do not require urgent or life-saving care — from 9:45pm on Wednesday to 8:15pm the following day.
Professor Spurrier said it was "concerning" the Queen Elizabeth Hospital emergency department was among dozens of exposure sites, the full list of which can be found here.
The sites also included a pharmacy in Fulham Gardens, two SA Pathology Collection Centres, Westfield Marion, Harbour Town outlets and Morphett Vale Stadium.
"They [contact tracers] are meticulously going through their records to look for the contact details of anybody who was in the emergency department or the area they call the fast track area and being able to send out messages directly to those people."
"They are also working through staff who might have been exposed during the time that the person was there, fortunately we do have a policy to make sure our staff are vaccinated against these sorts of infectious diseases."
Professor Spurrier is urging anyone who may have come into contact with the infected person to monitor for symptoms, which include a fever, cough, blocked or runny nose, conjunctivitis and a red rash which spreads across the body.
"The average incubation period from the date that you might have exposed is around about 10 days, but it can go anywhere from seven days up to 18 days," she said.
"If you do develop any symptoms at all, please get yourself tested but we do ask for you to ring ahead to the doctor or the hospital so they know you may have been exposed so we can put precautions in place."
Professor Spurrier said anyone born from 1966 onwards may have only had one dose of the measles vaccine, which may not appear on the Australian immunisation register.
"If you don't have definitive evidence of those two doses then it's not harmful to have another dose just to be on the safe side," she said.
Australian Medical Association SA president Professor Peter Subramaniam said the latest outbreak was concerning but people should not be alarmed.
He said measles spread quickly and urged people to check their vaccination status.
"The normal course of events if you get two vaccines as a child at twelve months and eighteen months... Those two doses protect about 99 per cent of people for life," he said.
"To protect the people who are most at risk, the rest of us have to make sure we get vaccinated."