The health authorities are concerned other people may have been exposed to the virus.
The adult was in public venues in Mitchelstown, including a primary care centre and a supermarket at the end of last month. The individual also spent some days in Clonmel, fearing a risk of the virus spreading.
The Health Protection Surveillance Centre (HPSC) has advised people to speak to a GP about their concerns.
The HPSC has been notified of 38 confirmed cases of measles since May, and eight are under investigation. Last week, a confirmed measles case was notified to the Department of Public Health in Cork.
The HPSC said the best way to prevent measles is by vaccination against the diseases, as part of the combined measles-mumps-rubella (MMR) vaccine that is administered free of charge to all children as part of the routine immunisation programme.
In areas where an outbreak is occurring, additional measures have been put in place to ensure all individuals in need of MMR can obtain it free of charge.
The HPSC said that all individuals travelling to Europe and other regions where measles continue to occur should ensure they are MMR-vaccinated if needed.
“Speak to your GP, if you are unsure about your vaccination status and if you should get the MMR,” it advised. It also pointed out that all children and young people going to language colleges or other summer activities should be up to date with MMR vaccines.
Investigation and control measures are being implemented in the HSE South and South East to identify those who may have been exposed to prevent further transmission and to ensure people are aware of the risk.
Public health consultant Kevin Kelleher said measles was highly infectious and spread easily so there was a “high chance” that individuals who had not been fully vaccinated with two doses of MMR vaccine would develop the disease if exposed.
“The time between exposure to measles virus and developing measles rash is normally 14 days,” said Dr Kelleher. “People are infectious from four days before the rash starts until four days after. If infectious cases are isolated early, the risk of transmission to vulnerable individuals decreases.”
Meanwhile, it emerged that people may have been exposed to the measles-infected person while shopping at SuperValu, New Square, Mitchelstown, on July 25, in the afternoon or early evening and on July 27, in the afternoon and evening.
The person also attended the Living Health Clinic on the Fermoy Road in Mitchelstown on July 28 in the afternoon or early evening. The adult was in Clonmel between July 23 and July 24 and from July 30 to August 3.