Four new cases of measles have been identified by health authorities following an alert last month over two incidents.
The recent cases were detected in Dublin, affecting two adults and two children.
They are believed to have likely developed the condition following contact with one of the two earlier cases at hospitals in Dublin.
Their emergence has prompted the Health Service Executive (HSE) to issue a public alert warning against the infection and guidance on how to avoid it.
Measles is a highly contagious disease that is spread easily. The time between exposure and developing a rash is usually 14 days, although over a range of 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.
The HSE requests people to continue to be vigilant. "Measles can be a serious illness and is highly infectious. The best protection is to be fully vaccinated with two doses of MMR (Measles, Mumps, and Rubella) vaccine," said Dr Helena Murray, specialist in public health medicine.
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, a 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.
Those who suspect they may have contracted the disease are advised to stay home, contact their GP and not allow visitors. Pregnant women who have been exposed to measles should seek medical advice as soon as possible.
