Health officials will investigate whether the incidence of adenovirus in many children who are part of a mysterious hepatitis outbreak is “incidental,” the US Center for Disease Control said Friday.
The research — involving a study of adenovirus in children who do not have liver disease — is a possible departure from the leading theory that adenovirus, a pathogen that commonly causes cold or flu-like symptoms, is solely responsible for the outbreak.
As researchers examine the liver biopsies of affected children and fail to find adenovirus, “this raises our suspicion that something else is going on here,” said Dr. Jay Butler, deputy director for infectious diseases at the U.S. Centers for Disease Control, on a media appeal Friday.
Nevertheless, adenovirus 41, a particular strain commonly associated with gastrointestinal distress, plays a “major role” in the agency’s leading hypothesis, Butler said, adding that previous infection with COVID or some other factor could also play a role. play.
As of October, 180 U.S. children with acute hepatitis of unknown origin, often with jaundice, have been reported in 26 states and territories, Butler said. The median age of those affected is 2. The number of reported cases has increased by 71 in the past two weeks.
Eight percent of cases in the US required a liver transplant, and six deaths are under investigation. More than 90% of patients were hospitalized, according to the CDC.
As of April 23, at least 160 cases had been reported in Europe, with about 10% requiring liver transplants and at least one death, according to the World Health Organization.
Many, if not most, recently reported U.S. cases were retrospective, meaning they occurred some time since October but were only reported recently, Butler said, adding that no bout of new cases has been reported.
While adenovirus 41 in particular “seems to play a role in these children,” questions have been raised about “cofactors that make infections more likely,” Butler said.
Researchers look at patients to see how many had previous COVID infection or whether they met criteria for MIS-C, a rare, multisystemic inflammatory condition reported in patients who have had COVID or have been in contact with those who , he added.
US medical officials in particular have been quick to implicate adenovirus as a possible cause, as it has been detected in nearly half of children with hepatitis of unknown cause. Other possible culprits include COVID and hepatitis A, B, C, D and E viruses, according to the CDC.
But adenovirus “does not fully explain the severity of the clinical picture,” according to a report from the World Health Organization in late April. “Infection with adenovirus type 41, the adenovirus type involved, has not been previously associated with such a clinical presentation,” the report said.
Common symptoms of adenovirus type 41 include diarrhea, vomiting, fever and respiratory symptoms, according to the WHO, and the strain is not known to cause hepatitis in otherwise healthy children. Other types of adenoviruses have been linked to liver failure, but only in immunocompromised children.
“Adenovirus is very common, so the fact that it’s very common and the fact that we haven’t seen the pattern before makes it important to differentiate” from other possible causes, Dr. Georges Benjamin, head of the American Public Health Association, told Fortune this week. “We should not end our search for other viruses.”
While active COVID infections were found in a smaller percentage of US and UK patients than adenovirus, in most cases no evidence of previous COVID infection was reported, or perhaps even sought.
Such tests are now underway in the UK, according to health authorities there. Of the 173 pediatric acute hepatitis patients in the US reported in the US last week, 12% had active COVID infection and 74% of the 19 patients tested showed signs of previous infection. The CDC is “in the process of obtaining” blood samples from children to test for COVID antibodies, Butler said Friday.
Other possible causes of the mysterious cases of hepatitis include a new strain of the adenovirus, exposure to a toxic substance and a new hepatitis virus, officials have suggested. It is also possible that the world is seeing a normal pattern of childhood hepatitis that has been previously underreported. Reporting hepatitis is not mandatory in the US, Butler said Friday.
This story was originally on Fortune.com