WA doctors are alarmed by a surge in cases of mumps, a highly infectious viral illness that is rarely seen today but can cause fatal complications such as meningitis and miscarriage.
Health Department figures show 19 cases have been reported in WA since late December compared with just two cases in the same period last year, with most occurring in older teens and young adults aged in their early 20s living in Perth.
The department said yesterday it was concerned by the spike in cases that did not appear to be linked, suggesting the virus was in wide circulation and there were many other cases not being detected.
Mumps is rarely seen because of the widespread use of the measles, mumps and rubella vaccine given to children.
"The department is not aware of any serious outcomes among these cases, although mumps infection can be associated with meningitis, encephalitis, hearing loss, pancreatitis and miscarriage," a spokeswoman said.
"Most of the cases have not been vaccinated against mumps, although a few received vaccine many years ago. Immunity to mumps vaccine can wane over time but most vaccinated people remain well- protected."
Australian Medical Association WA president Richard Choong said many young doctors would never have seen a case of mumps.
"This could almost be considered an old disease, so to have such a high number of cases in a short period is very unusual," Dr Choong said.
"What is really alarming is that it's not a cluster but seems to be floating out there in the wider community.
"It's a concern that in half of these cases the people have either never been vaccinated or only partially, so it reinforces the need for us to have very high rates of vaccination."
Symptoms of the mumps include swollen salivary glands behind and below the jaw, fever, headache, aching muscles, lethargy and painful testicles in men.
The department said people with symptoms should avoid contact with other people and see their GP.
It advised parents to ensure their children were up to date with their mumps vaccinations which were usually given as part of the MMR vaccine at 12 months and four years.
Young adults who had not received the MMR vaccine should see their GP.