Earlier this year, physicians in the United Kingdom raised alarm over an apparent surge in cases of unexplained severe acute hepatitis in children.
By late June, the U.K. reported 258 cases, 12 of which required liver transplants, up from about 20 in a normal year.
As of mid-July, 35 countries reported more than 1000 probable cases, including 22 deaths, with most of those cases occurring in Europe.
Canada reported 23 as of mid-August, two of which required liver transplants. An expert told CMAJ that's roughly the number you would expect to see given the size of Canada's population.
It's not unusual for the causes of severe liver inflammation in children to be unknown--by some estimates, up to half of such cases are unexplained. And it's still unclear whether the numbers reported globally reflect a true uptick in unexplained cases rather than increased attention to the issue.
Adenovirus, SARS-CoV-2 initially suspect
Early investigations suggested a link with adenoviruses, a group of more than 50 viruses known to cause cold symptoms, pink eye, gastroenteritis, and other common illnesses.
The United States Centers for Disease Control and Prevention (CDC) reported evidence of adenovirus infection in 45% of children with unexplained hepatitis from October 2021 to June 2022, with adenovirus 41 being the most common. Meanwhile, a U.K. study found adenovirus infection in 90% of cases.
Adenoviruses are known to cause hepatitis in immunocompromised children, but most of those...