Studies probe link between adenovirus and childhood hepatitis cases

Two new articles add to the circumstantial evidence that a common childhood virus may be involved in rare cases of hepatitis, but many questions remain .

< p class="css-at9mc1 evys1bk0">For months, scientists around the world have been investigating cases of severe and unexplained hepatitis, or inflammation of the liver, in previously healthy children . At least 920 probable cases have been detected in 33 countries since October, according to the World Health Organization. About 5% required liver transplantation and 18 deaths have been reported.

So far, explanations have remained elusive. A significant proportion of childhood hepatitis cases have always been unexplained. There is still no consensus on whether these cases have become more frequent, and it is unclear whether the recently reported cases, which remain rare, are part of a new medical phenomenon or share a underlying cause.

But more detailed case investigations are beginning to provide clues.

Two new studies, published Wednesday in the New England Journal of Medicine, report that two medical centers, one in Birmingham, Alabama, and the other in Birmingham, England, have seen an increase in the number of children with hepatitis unexplained acute illness within the past few months.

Research also presents more circumstantial evidence that adenovirus 41, which often causes gastrointestinal symptoms, may be a factor contributory. In both studies, adenovirus infections were detected in approximately 90% of children tested, and children who developed acute liver failure or required a transplant had higher mean levels of virus in their blood than those with less severe cases.

"I think adenovirus could be a player," said Dr. Helena Gutierrez Sanchez, medical director of the Pediatric Liver Transplant Program at the University of Alabama at Birmingham and author of one of the new papers. "That seems to be that common signal, not just in our cohort, but around the world."

But the evidence is far from definitive. And none of the studies found clear evidence that the virus was in the liver cells of any of the affected children, suggesting that if there was a link between adenovirus infections and hepatitis, it could not to be simple.

"I don't think it's a subtle point," said Dr. Saul Karpen, pediatric hepatologist at Emory University and Children's Healthcare of Atlanta, who wrote an editorial accompanying the two new articles. "I think that's a main point."

Not all medical centers have seen the same increase in cases, he noted, and a recent study by the Centers for Disease Control and Prevention found no evidence that unexplained hepatitis has become more common among American children in general.

The new cases do not necessarily represent "something new and scary", he said. "On the other hand, you can't ignore it."

Hepatitis has a variety of causes, including certain medications and medical conditions, toxins, high alcohol consumption and the hepatitis A to E virus.

Adenoviruses, a family of viruses that typically cause cold or flu symptoms, are not generally not associated with liver inflammation in otherwise healthy children.

But clinicians have detected adenovirus infections in many recent cases, including.. .