The HSE is urging parents to make sure their children are up to date with their MenB vaccines after three cases of meningitis were discovered recently.
A fourth patient has been classed as a "possible" case, while two people with the illness have died.
The MenB vaccine was introduced in Ireland for all children born on or after October 1st, 2016, because children under one year are at the highest risk of meningococcal B disease. All children are offered MenB vaccine at 2 and 4 months of age with a booster dose of MenB vaccine given at 12 months.
Dr Lucy Jessop, director of the HSE National Immunisation Office, explained the symptoms to look out for.
Dr Jessop told Newstalk: "Early signs or symptoms are things like fever, headache, neck stiffness, sometimes discomfort from the light, those are the signs and symptoms of meningitis... that information around the brain.
"But also it can even be diarrhoea and muscle pains and stomach cramps, cold hands and feet even though you have a fever, then people might be familiar with the pin prick rash or blood blisters. Some people might have seen pictures of the glass test, so if you cover the rash with a glass, and it doesn't go away."
