The Health Service Executive says there is a mumps outbreak in the west of the country, following a significant increase in the number of people diagnosed with the condition in recent weeks.
A total of 45 people have been affected by mumps in the HSE's western region in the last seven weeks.
The outbreak has impacted people aged between 15 and 29.
Mumps is spread by coughing and sneezing and can also be transmitted through direct contact with saliva.
It is an acute viral illness, with symptoms including fever, headache and painful, swollen salivary glands.
Mumps can also lead to complications like meningitis and can cause swollen testicles, which can lead to fertility problems in later life.
The HSE says immunisation though the MMR vaccine provides the best protection for people and it is urging those who have not had two doses of the vaccine to seek an additional dose.
People who are uncertain if they have had two doses are also being advised to get vaccinated as soon as possible, because it can take up to 28 days for the antibodies to take effect.
Treatment for mumps is focused on symptom relief with rest, fluids, and over-the-counter painkillers advised.
Anyone with the condition is being advised to stay away from school, college or work for five days after the first sign of symptoms.