A mystery spike in hepatitis cases seen in children in the UK is now occurring in the EU and US.
Health officials in Britain have identified 74 cases since January, with 6 UK children needing liver transplants as a result of the illness.
The typical viruses that cause hepatitis were not seen in these cases, puzzling health officials.
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The HSE has said less than 5 cases of the illness have been identified among Irish children so far.
Cases have also been found in the Netherlands, Denmark and Spain.
HSE National Clinical Officer Dr Ciara Martin said that the cause of the illness is unknown at the moment.
She explained on RTE Radio 1: "Hepatitis is just a medical term for inflammation of the liver and there are different causes of this.
"One of the most common causes is viruses and we know that there are a number of viruses that can particularly affect the liver.
"In some of these cases that we have seen in Ireland and across Europe, we're not picking up those viruses so that's why we're saying it's an unknown cause at the moment.
"The other reason why it might be happening is that it could be a different virus that that might be affecting a child in a different way and just happens to affect the liver."
Dr Martin also listed general symptoms of the illness for parents to look for in their children.
"Anything that affects your liver is going to give you general symptoms," she said.
"We commonly see symptoms such as nausea, vomiting and diarrhea when you have a tummy bug and you can get that in this case.
"But other key symptoms to look out for would be where the child's urine is darker than normal and maybe with poop, the colour is paler than normal.
"Skin may be yellow and the child might be itchy.
"Those last ones indicate that it might be a virus or it's a hepatitis affecting the liver."
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