The health executive has confirmed that 13 cases of measles have occurred in separate areas of the country.
In total, 19 cases have been identified and 13 confirmed thus far, with six more likely diagnoses.
As reported by the HSE, all individuals affected are under the age of 30, with most in the 15-19 range.
Officials believe that the patient zero came from an European country where an outbreak of the highly infectious disease is developing.
Symptoms include high fever, a cough, a runny nose, and a red rash that starts on the head and spreads down the body.
While there are no immediate reasons for concern, health officials recommend that any suspected case is reported promptly to minimize the risk of further contagion.