What is hepatitis, and how many children has it sickened?

The Centers for Disease Control and Prevention said on May 20 that it is investigating 180 cases of severe hepatitis of unknown cause in children dating back to October. Cases have been reported in 36 states and territories. Hepatitis refers to inflammation of the liver, an organ that performs vital functions such as processing nutrients, filtering blood and fighting infections. That’s an increase of 71 from the 109 cases in the United States reported May 6. The vast majority of those are not new, but involve illnesses just now being reported, the agency said in a statement. “Some may ultimately wind up not being linked to the current investigation,” the CDC said. The agency is posting weekly updates on its website. Federal health officials issued an alert on April 21 about the first cases to be recognized in this country, a cluster of nine children with hepatitis of unknown origin in Alabama, and asked physicians to report any similar suspected cases. Those children had also been infected with an adenovirus, but officials said a link between the two has not been established. As of May 11, the European Centre for Disease Prevention and Control said there have been about 450 cases of the hepatitis of unknown origin among children reported worldwide. At that time, the United Kingdom had more cases than any other country, with 176. In the United States and the U.K., the most common types of viral hepatitis are hepatitis A, B and C, which were ruled out among these children. Other causes of hepatitis include alcohol use, toxins, some medications and certain medical conditions, including viral infections.

What are the symptoms of hepatitis in children?

Officials stress that severe hepatitis in young children remains rare but urge parents to be on the alert for unusual signs, including jaundice — yellowing of the skin and the whites of the eyes — dark urine and light stool. The Alabama children’s symptoms ranged from gastrointestinal problems like vomiting and diarrhea to upper respiratory symptoms, according to the CDC. Eight showed yellowing of the whites of their eyes. Seven had enlarged livers, and one had encephalopathy, or evidence of impact on the brain, the CDC said. Three of the children suffered liver failure, and two needed liver transplants. All have recovered, officials said. In the U.K., most of the children were under 5, and their families reported similar symptoms, including vomiting, stomach pain and diarrhea over a two-week period, and then the development of yellow eyes or skin. A few had other symptoms, such as headaches and sore throats, and a very small proportion had fever, according to Elizabeth Whittaker, a pediatric infectious-diseases specialist at Imperial College in London who is assisting with the U.K. investigation. But young children get gastrointestinal symptoms all the time, so clinicians urge parents not to worry unless those persist for more than three or four days or are accompanied by other symptoms such as lethargy and yellowing of the eyes and light-colored stool.

What is causing these recent cases of hepatitis in children?

Doctors have not yet pinpointed the cause but are looking closely at the possible involvement of a pair of viruses: One is adenovirus — a common family of viruses that cause symptoms ranging from the common cold to stomach upsets and pinkeye. About half the U.S. children whose hepatitis cases are under investigation had a confirmed adenovirus infection, officials said. “It continues to be a strong lead,” the CDC said in its May 18 statement. One adenovirus subtype, called 41, which causes pediatric gastroenteritis typically with diarrhea, vomiting and fever and often accompanied by respiratory symptoms, was found in five of the nine sick children in Alabama. The other four didn’t have sufficient concentrations of virus in their blood samples to be tested. Adenovirus 41 was also found in 18 of 18 U.K. children who had enough virus in their samples for testing. While there have been reports of hepatitis in immunocompromised children with adenovirus infections, the virus is not known to cause the illness in otherwise healthy children. . In the past, doctors may have overlooked adenovirus-related hepatitis in otherwise healthy kids, according to Ryan Fischer, pediatric gastroenterologist and transplant hepatologist at Children’s Mercy Hospital in Kansas City, Mo. If a patient has signs of hepatitis but it is mild and resolves on its own, doctors do not routinely do viral studies beyond looking for hepatitis A, B or C. “It could be that we miss many cases … because we don’t check for it and the children recover uneventfully,” Fischer said. Investigators said May 20 that lab testing of the adenovirus 41 genome has peaked their interest in the possibility that the virus is operating in concert with another pathogen to cause hepatitis. The second virus getting a closer look is the coronavirus , which some doctors theorize may have contributed to liver inflammation through an old infection or a co-infection that has triggered the immune system to overreact. None of the children in Alabama had a documented history of having had covid-19, but officials are working to determine through blood tests whether some may have had prior undiagnosed infections. In addition, none of the children in Alabama had received a coronavirus vaccine, officials said. “Covid-19 vaccination is not the cause of these illnesses,” said Jay Butler, the CDC’s deputy director for infectious diseases. “We hope that this information helps clarify some of the speculation circulating online.” At a recent World Health Organization briefing, Philippa Easterbrook, an infectious-disease specialist, said investigators are looking into “all possible infectious and noninfectious causes.” CDC officials said they have not found a common link to other factors , such as environmental exposure, medications or family pets. Ongoing studies will focus on understanding the pathogen and the affected children’s immune responses and genetics, as well as on comparing the rate of adenovirus among children hospitalized with hepatitis with the rate among other hospitalized children.

What hypotheses are being investigated about the possible role of the coronavirus?

Investigators are exploring whether young children who had fewer social interactions during the pandemic may have been more susceptible to adenovirus. They’re also looking at whether a more lethal adenovirus might have emerged and whether a co-infection with the coronavirus could make adenovirus “manifest in a way that has not been commonly seen before,” said Butler, of the CDC. Experts say it’s unlikely that the cases were directly caused by SARS-CoV-2, the virus that causes covid-19, because it has been around for two years and so many children in the United Kingdom and the United States have antibodies against it.

How worried should parents be about these cases?

Officials are urging parents to see a pediatrician if children are exhibiting any unusual symptoms, including abdominal discomfort, vomiting, dark urine and pale stool, but not to panic. “As a parent, I’m not sure we need to spend our time worrying about this condition,” said Fischer, the Kansas City physician. “This is still rare enough that we don’t need to implement new steps.” Whittaker, of Imperial College, said it is normal for children to have vomiting or diarrhea for a few days, but parents should seek medical attention for a child having persistent symptoms after more than three to four days. Parents should also seek help before that time if their child is drowsy, unresponsive or irritable or not able to keep water down, she said.

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Unusual cases of hepatitis in children: Your questions, answered

By Frances Stead Sellers

and

Lena H. Sun

Updated May 24, 2022 at 8:26 a.m. EDT|Published May 5, 2022 at 7:00 a.m. EDT

A cluster of acute hepatitis cases among previously healthy children around the world, including 180 in the United States, has created concerns for doctors, scientists and parents. The cause is unknown, but some scientists say they may be linked to a common virus that causes colds, gastrointestinal distress and other minor ailments. Disease detectives also say they may also be uncovering a phenomenon that has existed, unrecognized, for years.