The mystery of a childhood hepatitis surge

Doctors in the United States and around the world remain baffled about a sudden uptick in young children hospitalized with severe hepatitis. The World Health Organization (WHO) has reported at least 169 cases globally since October, with nine cases across the United States. Altogether, 17 children have needed emergency liver transplants, and at least four have died.

Hepatitis is the medical term for the inflammation of the liver, the organ that removes toxins and helps with food digestion. Many people might not feel symptoms, but others experience vomiting, diarrhea, and jaundice.

Children can get the condition, but the recent spike is surprising because severe hepatitis is uncommon among children and teens and unheard of among healthy kids. Further confounding doctors is that after running through their checklists, they realized none of the kids fit the profile of a typical hepatitis patient: All tested negative for the traditional hepatitis viruses (hepatitis A, B, C, D, and E), none knew or lived close to each other, and none had any family history of liver issues. While at least one theory might explain the rash of cases, health experts are still trying to nail down the cause.

Dr. Saeed Mohammad, director of the Pediatric Solid Organ Transplant Center at Children’s Hospital at Vanderbilt, says his hospital has seen seven hepatitis cases in children since October. It normally sees two a year. All of the patients came in with alarmingly high liver enzyme numbers, a gauge of liver health. Mohammad says a normal liver enzyme number is anything below 30, and anything above 500 would get reported to U.S. health officials. The sick children his hospital has seen had liver enzyme numbers between 1,000 and 3,000.

What’s behind the surge in cases? The prevailing theory among doctors and health experts pins blame on the adenovirus, a common virus type anyone can catch that is often associated with upper respiratory infections, like the common cold. Adenovirus type 41 can give kids hepatitis, but right now no one’s sure if that’s the culprit. Many of the sick children tested positive for adenovirus, and the WHO reported 18 of them had adenovirus type 41.

But Mohammad cautions doctors don’t know which strain of adenovirus all the patients have. And the adenovirus test is known for being sensitive — it can detect traces of an adenovirus that caused a cold weeks ago. If that’s the case and all the kids had previous colds, the adenovirus could be a red herring.

Conor Meehan, a senior lecturer in microbiology at Nottingham Trent University in the United Kingdom, wrote at the academic news site The Conversation that while adenoviruses can cause hepatitis in immunocompromised kids, it’s extremely rare for healthy kids to be hit this hard.

“If adenovirus is the cause of these cases, it could mean that a new variant of adenovirus has emerged that more easily causes hepatitis,” he wrote.

Some doctors also wonder whether the severe reaction could be the result of two or more viruses interacting such as adenovirus and the coronavirus. (Most of the affected children had not received a COVID-19 vaccine, so a vaccine link isn’t likely.) Interestingly, COVID-19 can cause hepatitis, and the WHO reported that 20 of the 169 hepatitis patients tested positive for COVID-19. Nineteen tested positive for a co-infection of COVID-19 and adenovirus.

Still, Mohammad thinks COVID-19 is a tangential problem and not likely the root cause. “It’s been two years of COVID, and it’s not like we’ve seen an outbreak of hepatitis among COVID patients,” he said.

The average parent needn’t be too worried. So far, the number of sickened children is tiny compared with the overall population, and most have recovered with minimal hospital intervention. Mohammad is currently chairing a committee to investigate the cause and trends of this recent spike, and he wonders if the cases have already peaked.

“We haven’t had a case in six weeks, so I wouldn’t limit activities because of this,” he said. “If your kid is sick, go to the pediatrician.”