Health bosses are warning people to get themselves vaccinated following a sharp rise in mumps across Sussex.
The Argus has learned there were 103 confirmed cases of the virus in 2013 – nearly two people per week.
That is almost double the 52 recorded for the whole of 2012 with five more cases already confirmed so far this year.
There are now fears of an outbreak across the county unless more people get themselves protected.
Many cases have involved teenagers and young adults who did not have the measles, mumps and rubella (MMR) vaccination when they were children because of now-discredited fears about its link with autism.
Take up rates for both doses of the vaccine dropped steeply in the immediate aftermath of the scare in the late 1990s, meaning thousands of people across Sussex are still at risk.
The mumps increase follows anoutbreak of measles in 2012, which affected more than 330 people in the county.
Measles cases have fallen dramatically since then, with just four confirmed cases in 2013.
It is believed the actual number of people with mumps and measles is higher than recorded because not every case is sent for testing.
Residents are being urged to make sure they get both doses of the vaccine to try to stop the viruses 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.
Take up rates in Sussex currently range between 86% and 88%.
Brighton and Hove City Council public health consultant Max Kammerling said an outbreak of mumps this year remains a possibility and that “it is extremely important that people get themselves vaccinated”.
He added: “When you have an area that has a low immunisation rate for MMR you are going to have cases of these infectious diseases.
“The measles outbreak was very distressing for all the patients and families affected and we don’t want a mumps outbreak to add to it.
“Both measles and mumps continue to affect some children locally each year.
“A substantial effort has gone into improving our overall vaccine uptake rates, and we are now very close to achieving the level required for herd immunity – when it will be hard for the diseases to spread in the community.
“However, older children who have not received the full course of vaccination remain at risk, and both these diseases can be very unpleasant to catch, and have long term consequences.
“For their protection, parents should check the immunisation history of their older children and if they have not had the full course of MMRvaccine, should visit their GP in order to get immunised.”
Mumps is an acute viral illness which is transmitted through airborne droplets from the coughs and sneezes of infected people.
It usually takes 16 to 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 the onset of symptoms.