Last month it was revealed one child died and another had to have a live transplant.
A second child has now had to go to the UK for a transplant as the number of probable cases has risen from eight to twelve.
The Health Protection Surveillance Centre (HPSC) said that since March twelve probable cases of children with hepatitis of unknown cause have been identified in Ireland and a small number of children are under investigation.
"This is more than would usually be expected over this period of time. The children affected have no links to the other children involved.
"To date no single virus has been identified in all cases. Investigations are currently ongoing to identify the cause of these illnesses.
"All probable cases are in children between the ages of one and 12 years of age and all have been hospitalised. Two children have received a liver transplant and there has been one death associated with this disease.
"In the UK, health authorities have also reported an increase in hepatitis of unknown cause in children. Investigations are underway in the UK to determine the cause of the illness. Information gathered thus far from the UK investigations suggest that the recent cases of hepatitis may be linked to adenovirus infection, however this theory is still under investigation.
"The Irish cases have no links to the UK cases, and only one had a recent travel history to the UK before onset of symptoms."
It said the common viruses that cause hepatitis (hepatitis viruses A, B, C, and E) have not been detected in any of the cases. One area being explored is whether the hepatitis cases are linked to an increase in infections caused by adenovirus, a common cause of childhood and adult illnesses typically causing mild cold- or flu-like illness, or diarrhoea.
Adenovirus infections rarely cause hepatitis. Other possible causes such as another infection (including Covid-19) or something in the environment are also being investigated. In Ireland, as in other countries, investigations are underway to determine if current or prior Covid-19 infection may increase the risk of this disease in some children. None of the Irish cases who were tested on admission to hospital had evidence of Covid-19 infection at that time.
The majority of the cases had not received Covid-19 vaccination. Ireland is liaising closely with ECDC, UK and WHO colleagues in efforts to identify the cause of this illness.
GPs and paediatric consultants are aware of the recent increase in cases of hepatitis amongst children and will be alert to identify any further cases that may develop.
Parents are advised to go to their GP if their child develops symptoms of hepatitis. Symptoms of hepatitis can include:
- pale, grey-coloured poo (stools)
- dark urine
- yellowing of the eyes and skin (jaundice)
If their child has any of these three symptoms, they should contact their GP without delay. The GP will assess the child and refer on for further assessment as indicated.