The World Health Organization (WHO) reported that 12 countries have reported cases of hepatitis of unknown origin in children. In all, so far, 169 cases have been reported, with 17 liver transplants. At least one child died.
The UN health agency said that as of 21 April, acute cases of hepatitis had been reported in the UK (114), Spain (13), Israel (12), the US (9), Denmark (6), Ireland ( 5), Netherlands (4), Italy (4), Norway (2), France (2), Romania (1) and Belgium (1).

Credit: Mseidelch/istockThe European division of the WHO leading the investigation into the mysterious outbreak of hepatitis in children
Possible causes
The cases that mainly affect Europe raise several questions. Severe hepatitis in previously healthy children is not common.
What makes these cases of severe liver inflammation even more mysterious is that they are not being caused by the typical hepatitis A, B, C, D, and E viruses.
It is suspected that hepatitis may be triggered by a new strain of adenovirus, a common cold virus, or even the coronavirus.

Credit: Blackdovfx/istockThere is a suspicion that hepatitis may be triggered by a new strain of adenovirus
Both the UK and the Netherlands have reported that they are seeing increased circulation of adenoviruses, which adds to the evidence that these viruses may be playing a role.
At least 74 of the affected children have tested positive for adenovirus infection. Affected children range in age from 1 month to 16 years, although most are younger than 10 years and many are younger than 5 years.
Adenoviruses normally attack the respiratory tract, although some — including type 41 — can trigger gastroenteritis, an inflammation of the stomach and intestines that induces diarrhea. Adenovirus 41 has been associated with hepatitis in immunocompromised children, but has not been seen to cause the disease in previously healthy children.
Authorities have ruled out any possibility that Covid vaccines could be involved in these cases. The vast majority of children have not been vaccinated, the WHO statement said.