A recent increase in unexplained cases of hepatitis among children has led to concern among parents, with the first death reported in Ireland from an initial six cases. So what do we know so far and what are health officials trying to find out?
What is behind these hepatitis cases?
Hepatitis is an inflammation of the liver commonly caused by viruses known as hepatitis A, B, C or E. But none of these have been detected in recent cases.
United Kingdom health authorities advanced several possible theories for what could be causing the illnesses, the most likely being a link to adenovirus infection.
Normally adenoviruses in children lead to mild illnesses such as common colds, flu or sore throats. Infections of adenovirus have been found in more than half of children with unexplained hepatitis in Britain, as well as many of the suspected cases under investigation in the United States.
Other theories about what might be causing the cases include a new variant of adenovirus, a side effect of coronavirus infection, toxin or some other form of environmental exposure.
Contact tracing to see if affected children in Ireland had come into contact with any of the same foods, or a particular toy or activity, has yielded no connections to date.
How many cases are there?
The Health Service Executive has said there are six probable cases of children in Ireland with unexplained hepatitis. All six have been hospitalised, with one dying and another requiring a liver transplant.
The children are aged between one and 12 years old.
Globally, the European Centre for Disease Prevention and Control has recorded approximately 450 suspected cases of children with unexplained hepatitis. That includes more than 100 cases across the European Union, 163 in Britain and 109 in America.
How severe is the illness in children?
Health experts have said the illness appears to be more severe than normal. There have been 11 deaths in Indonesia, five in America, five in Palestine and the recently confirmed death in Ireland.
The US Centre for Disease Control has said in nine out of 10 cases under investigation children had been hospitalised, with 14 per cent requiring liver transplants.
While there have been no deaths in Britain, 11 children received liver transplants. At least half of the 163 children in Britain had been discharged from hospital or recovered fully as of the start of this month.
When did this all come about?
The alarm around the concerning new hepatitis cases was sounded by Britain last month, where authorities had begun to notice an increase in unexplained hepatitis among children from March.
Since then health officials, clinicians and scientists in various countries and agencies have been working to try and nail down what is causing the new cases and why they appear to be more severe. But it may take time before definitive answers emerge.
Could this be linked to Covid-19 vaccinations?
No, scientists and medics have emphatically ruled out any link between the unexplained hepatitis cases in children and the vaccine. In the UK, where officials have a significant amount of early data, the vast majority of children being treated for hepatitis had not even received the vaccine.
What are the symptoms of hepatitis?
The most common symptoms of hepatitis include jaundice (where the skin or whites of the eyes appear to turn yellow), dark urine, pale or grey coloured stool and itchy skin.
The HSE has advised parents to contact their GP if concerned about potential hepatitis symptoms in their children.