The HSE says 33 cases of measles have been confirmed in Ireland since May.
It comes after the agency last month confirmed details of an outbreak in in Co Kerry.
Most of the cases were in children under the age of 10, and the HSE says it is continuing to implement control measures to limit the outbreak.
People who are vaccinated with two doses of the MMR vaccine are normally protected, but the health service is advising people to be extra vigilant.
Babies younger than 12 months old, non-immune pregnant women and those with a weakened immune system are most at risk.
Dr Kevin Kelleher, HSE Consultant in Public Health, explained: “Measles is highly infectious, and if cases are isolated early, the risk of transmission to vulnerable individuals decreases.
"The time between exposure to the virus and developing measles rash is normally 14 days (range 7-21 days). People are infectious from four days before rash starts until four days after," he added.
As well as the rash, people are urged to be vigilant for symptoms such as a high fever, cough, runny nose and red eyes.
