An outbreak of mumps in Perth has worsened, with health authorities confirming 30 cases since late December compared with the usual handful in a year.
Several patients have been admitted to hospital, though none has become seriously ill.
The Health Department's latest Virus Watch bulletin said there had been three new cases in the past week and urged GPs to be on the lookout for patients with the highly infectious viral illness. It said most of the Perth patients had been infected locally and were older teenagers or adults aged in their 20s and 30s, and many were partially or fully vaccinated against mumps.
A department spokeswoman said yesterday that none of the confirmed cases was in young children.
"We are not aware of any cases with serious complications, although a few cases have been admitted to hospital with complications, including orchitis (swollen testicles) in men and meningitis," she said.
Although mumps is highly contagious, it is rarely seen any more because of the widespread use of the measles, mumps and rubella vaccine in childhood.
But if untreated, it can lead to serious complications including meningitis, miscarriage, encephalitis, hearing loss and pancreatitis.
The department said the rise in cases did not appear to be linked, suggesting the mumps virus was in wide circulation and there were many other cases in the community not being detected. It said GPs should test for mumps in all patients showing signs, regardless of whether they had been vaccinated, using blood and urine tests and throat swabs.
Symptoms of mumps include fever, loss of appetite, tiredness and headaches, followed by swelling and tenderness of the salivary glands.
The infection spreads when a person breathes in the mumps virus, usually after someone infected has coughed or sneezed.
Doctors say people born after 1965 need to ensure they received two doses of the MMR vaccine and not just one, which might not provide enough protection.
The department this week also urged GPs to encourage pregnant women to be vaccinated against the flu after its regular surveillance found cases of flu-like illnesses had increased in recent weeks.
A survey showed that last year only 23 per cent of pregnant women took up the free flu vaccine but most said they would have it if their doctor or midwife recommended it.