Health bosses have warned mumps is on the rise across Sussex.
Dozens of people have been struck down this year by the virus which can lead to meningitis and inflammation of the brain in rare cases.
The number of cases registered this year is already outstripping the total for the whole of 2012.
It is feared the large number of visitors expected to head to Sussex during the summer may lead to an increase in infections.
Residents are being urged to make sure they get both doses of the measles, mumps and rubella (MMR) vaccine to try to stop the virus from spreading.
Around 95% of a population needs to be vaccinated in order to protect vulnerable members of the community, such as babies and those with lowered immune systems, from becoming infected.
The rise in cases follows an outbreak of measles last year, which affected more than 330 people across the county.
Figures from Public Health England show there have been 25 confirmed cases of mumps in Brighton and Hove, 23 in West Sussex and nine in East Sussex.
There were 52 cases of mumps reported across Sussex through all of 2012.
Brighton and Hove public health consultant Max Kammerling said: “The vaccine protects not just against measles but also against mumps and rubella.
“We are now also seeing an increase in the number of cases of mumps in older teenagers and young adults.
“Mumps can be a very uncomfortable condition. It can also result in meningitis, or even an inflammation of the brain itself, which, although rare, can have long term devastating consequences.
“This highlights the need for people who have not had the MMR vaccine to visit their GP as soon as possible, in order to protect themselves from any of these conditions.”
Mumps is an acute viral illness which is transmitted through airborne droplets from the coughs and sneezes of infected people.
It usually takes 16-18 days for the symptoms of mumps to develop, after coming into contact with someone who has the virus.
Individuals are infectious two days before and four days after onset of symptoms.
A spokesman for Public Health England said: “If your child has not had the MMR vaccine, the upcoming summer holidays is a good time to contact your GP to get them vaccinated.
“We are advising parents to be aware of the symptoms of mumps.
“Should their children become symptomatic they should see their GP and avoid social contact for five days.”
Swollen glands is the most common symptom of mumps but other signs include headache, joint pain, mild abdominal pain, feeling tired, loss of appetite and a high temperature.