The Centers for Disease Control and Prevention issued a public health alert to physicians nationwide, asking doctors to be on the look out for unusual cases of severe liver disease in children.
The agency said in its advisory Thursday that nine cases of hepatitis, or liver inflammation, have been reported in Alabama in children aged 1 to 6, and NBC News reports an additional two have been identified in North Carolina, according to the state's health department
Dozens of cases have been reported in recent weeks in children in Britain and across Europe. The usual viruses that cause infectious hepatitis were not seen in the cases, and scientists and doctors are considering other possible sources.
“Mild hepatitis is very common in children following a range of viral infections, but what is being seen at the moment is quite different," said Graham Cooke, a professor of infectious diseases at Imperial College London. Some of the children in the U.K. have required specialist care at liver units and a few have needed a liver transplant.
The liver processes nutrients, filters the blood and fights infections. The infections caused symptoms like jaundice, diarrhea and abdominal pain. Hepatitis can be life-threatening if left untreated.
While it's unclear what's causing the illnesses, a leading suspect is an adenovirus.
There are dozens of adenoviruses, many of them associated with cold-like symptoms, fever, sore throat and pink eye. U.S. authorities said the nine Alabama children tested positive for adenovirus and officials there are exploring a link to one particular version — adenovirus 41 — that’s normally associated with gut inflammation.
The CDC's advisory Thursday urges pediatric doctors to consider adenovirus testing.
Public health officials ruled out any links to COVID-19 vaccines, saying none of the affected children were vaccinated.
The WHO noted that although there has been an increase in adenovirus in Britain, the potential role of those viruses in triggering hepatitis is unclear. WHO said there were fewer than five possible cases in Ireland and three confirmed cases in Spain, in children aged 22 months to 13 years.
The U.N. health agency said that given the jump in cases in the past month and heightened surveillance, it was “very likely” more cases will be detected.