Devon County Council has issued advice to parents across East Devon following a rise in cases of mumps.
Young people aged between 15 and 24 account for more than half of recent cases.
The council says many of those impacted currently attend local schools and nearby universities.
It has teamed up with Public Health England to raise awareness about the highly contagious infection.
In a joint statement sent to parents via schools, the authorities say: “If your child has not been vaccinated, we would recommend they receive two doses of the measles, mumps and rubella (MMR) vaccine to ensure they are protected.
“It is easy to check if your child has had the vaccine by contacting your GP and asking if they have had two doses of MMR. If not, then you can arrange for your child to have their MMR vaccine at your GP surgery.”
Spread in the same way as colds and ’flu, mumps is easy to catch. It is best-known for causing painful swellings at the side of the face, under the ears, but this may not always be present.
Other symptoms can include a high temperature with joint pain and loss of appetite.
The council advises parents: “It is important that you contact your GP if you think your child may have mumps so that a diagnosis can be made and advice given.”
If your child currently has mumps, you can stop it spreading by washing hands with soap, catching sneezes using tissues and by keeping your youngster away from school.
Mumps infections take between one and two weeks to clear.