The Health Service Executive has confirmed an outbreak of measles in Dublin, with ten cases identified since February.
Anyone who thinks they may have the illness is being advised to stay at home and to contact their GP for advice.
The HSE said it is a community outbreak of measles affecting adults and children.
They said recent cases involved young adults working in Dublin city centre in the areas of Parnell Street, Dame Street and Baggot Street.
Travel to France was also identified as a risk.
Measles is a serious illness and is highly infectious. The best protection is to be vaccinated with MMR (Measles, Mumps, and Rubella) vaccine.
The HSE has advised that anyone planning to travel abroad should make sure they are protected from measles.
Those who have not been vaccinated with MMR vaccine or have not had measles in the past are at risk of measles.
If unsure whether they had the vaccine they should speak to their GP about getting the MMR vaccine before travelling.
Measles symptoms include fever, red rash, red eyes, cough and runny nose.
The rash usually starts a few days after onset of illness. It typically starts on the head and spreads down the body.
There is a risk of developing measles for up to 21 days after contact with a case of measles.
The HSE has warned that people who are sick should not attend settings such as crèche, school, work or religious gatherings until they have recovered from illness.