The HSE is dealing with a measles outbreak in Dublin, with 10 cases recorded in adults and children identified in Dublin since February.
The HSE said recent cases have involved young adults working in Dublin city centre in the areas of Parnell Street, Dame Street and Baggot Street.
Travel to France was identified as a risk.
Anyone who thinks they may have the illness is being advised to stay at home and to contact their GP for advice.
Measles is a highly contagious disease that is spread easily. The time between exposure and developing a rash is usually 14 days, although it can range from seven to 21 days.
However people are infectious from four days before a rash begins to appear, and until four days afterwards. Measles can cause chest infections, seizures, ear infections, swelling and potentially, damage to the brain.
Vaccine
People at increased risk of getting measles are those who are not fully vaccinated with two doses of MMR vaccine or have not had measles in the past.
Symptoms include a high fever, coughing, runny nose and red eyes.
The red rash associated with the condition begins on the head and spreads down the body.
This normally starts a few days after the onset of illness.
The rash consists of flat red or brown blotches which can flow into each other, and lasts between four and seven days.
Vomiting, diarrhoea and stomach pain can also occur.
The HSE has advised anyone who thinks they may have measles to stay at home and phone their GP for advice.
People who are sick should not attend any congregated settings such as crèche, school, work or religious gatherings until they have recovered from illness.