A mysterious liver illness showing up in kids in both the UK and the US .. a new Covid variant issue or something else?

Health officials in several countries are investigating mysterious cases of severe liver disease in children, and they think it may be related to a kind of virus usually associated with colds.

The U.K. has been investigating at least 74 cases in which children came down with hepatitis, or liver inflammation, the World Health Organization said Friday.

Three similar cases in Spain and a few in Ireland are being investigated, the WHO said. Meanwhile, U.S. health officials say they are looking into nine similar cases.

All were in Alabama, but officials say they are looking to see if there are more elsewhere. “Given the increase in cases reported over the past one month and enhanced case search activities, more cases are likely to be reported in the coming days,” WHO officials said in a statement.

The U.S. children ranged in age from 1 to 6 years old, and two required liver transplants. The European cases are in a similar age range, though some have been older, WHO officials said. The WHO first became aware of the unusual illnesses early this month, when they learned of 10 children in Scotland with liver problems.

One got sick in January and the nine others in March.

All became severely ill and were diagnosed with hepatitis after being taken to the hospital.

There is speculation—and that’s all it is at this point—that the cause of this mysterious pediatric liver ailment may be a variant form of #SARSCoV2 or a previously unknown adenovirus.