Children and students are at increased risk of mumps as they return to school or college after the summer holidays, experts have warned.
Health watchdogs have also renewed appeals to parents to make sure that their children are given the MMR vaccine to immunise them against mumps.
More than 1,600 cases of the disease have already been recorded this year, with some victims in their 50s or 60s.
Outbreaks were reported in the community, schools, universities, private homes and other settings.
The country’s disease watchdog, the Health Protection Surveillance Centre (HPSC), fears that as schools and universities reopen “there is a potential for increased numbers again as the close social contact in these settings can contribute to spread”.
Mumps is a virus that spreads in a similar way to colds and flu.
It often causes a fever and swollen glands and passes without causing any more serious symptoms.
But in some patients it can trigger more serious illness such as swelling of the vital organs. There is no treatment and therapy is based on relieving symptoms.
The MMR (measles, mumps and rubella) vaccine is 88pc effective but there is increasing evidence it may wane over time.
Despite this, it remains the only way to prevent or minimise the risk of infection and complications associated with mumps. The HPSC said all children should receive the vaccine when they are aged 12 months.
Any child over 12 months who has missed the jab should get it now from their GP. It is free of charge to all children and during the outbreak period for teenagers and older adults for whom it is indicated.
In the first nine weeks this year, 451 mumps cases were notified compared to 60 for the same time period in 2018.
Meanwhile, there is growing concern over measles in Ireland after the UK formally lost its measles-free status.
Measles was deemed officially eliminated in the UK a decade ago, but falling vaccination rates have led to a dramatic re-emergence of the potentially deadly disease.
In some parts of London, one in four children in primary school has not had the initial MMR vaccination or the booster jab.
The HPSC said it was concerned by detection rates in Ireland, where the HSE was notified of 21 suspected cases in the first two months of this year. There has been a 43pc rise in the number of measles cases between 2013 (53) and 2018 (76).
This year, the most significant outbreaks have been in the north west, with at least six cases linked to a single outbreak in Donegal.
Another outbreak came among young adults working in the Dublin city centre area.
The HSE stressed that measles is highly infectious and severe cases can result in death. “The best protection is to be vaccinated with MMR vaccine,” a spokesperson said.