The WA Health Department has issued a measles alert after a confirmed diagnosis for an unvaccinated secondary school student who returned to Perth after being infected overseas.
In a statement, the department said prior to the diagnosis - and while infectious to others - the student attended Perth Waldorf School in Bibra Lake.
The department warned that a substantial number of students exposed at the school had not been vaccinated against measles, and because the school has a metropolitan-wide catchment, it's likely additional cases of measles will occur in Perth over the coming weeks.
The campus of Perth Waldorf School also includes pre-school and primary school students, and the department said it cannot exclude the possibility of incidental exposure to younger students.
The school has been working closely with Public Health staff in notifying parents of the potential exposure.
Prior to diagnosis, the case was also in the Midland area on Tuesday afternoon on July 25 and on Sunday afternoon on July 30, and may have exposed people there.
Director of Communicable Diseases, Dr Paul Armstrong said measles is highly contagious, and that approximately nine out of 10 susceptible persons in close contact with a measles patient would develop it.
"The illness is spread by tiny droplets, released when infected people cough and sneeze," Dr Armstrong said.
"Anyone who thinks they are infected should call ahead and mention their possible contact with measles so they can be isolated when they arrive at the GP surgery or Emergency Department, to prevent infecting other patients and staff.
"A person is considered immune to measles if they have previously received two doses of a measles vaccine or were born before 1966."
The department advises that early symptoms of measles include fever, cough, runny nose and sore eyes, followed about three days later by a red blotchy rash.
The rash usually starts on the face and spreads to the rest of the body. Measles can be especially severe in infants and people with poor immune systems.
The department said people who develop a fever with other symptoms - including cough, runny nose, sore red eyes and a rash - within two to three weeks of potential exposure to someone with measles, should stay at home and consult their doctor.
Naturally occurring measles has been eliminated from WA for about 20 years but the department said occasional cases and small outbreaks have been associated with tourists or WA residents who are infected overseas.
Complications following measles can be serious and include ear infections and pneumonia in about 10 per cent of cases. Around 40 per cent of cases require hospitalisation and about one person in every 1,000 will develop encephalitis, an inflammation of the brain.
