A mysterious form of hepatitis has appeared in more than 100 children

ARI SHAPIRO, HOST:

The Centers for Disease Control and Prevention said today it's investigating more than 100 potential cases of severe hepatitis in children, including five deaths. Cases have been reported in 25 states and territories, but the cause of the liver illness remains unknown. Several hundred similar cases have been reported in more than two dozen countries.

NPR health correspondent Maria Godoy is covering this story for us. Welcome.

MARIA GODOY, BYLINE: Hi, Ari.

SHAPIRO: What more can you tell us about these cases in the U.S.?

GODOY: The CDC is looking into 109 cases. All of the children were previously healthy. Hepatitis is a swelling of the liver, and in nearly all of these cases, the injury to the liver was severe enough that the children needed to be hospitalized. Most of the children have recovered, but, you know, some of the more - but 14% did end up needing a liver transplant, and, unfortunately, five of the children died.

SHAPIRO: This has happened so quickly. When the CDC first issued the alert, it was just two weeks ago, and there were only nine cases. What's behind the big jump?

GODOY: So these nine cases were first seen in Alabama between October and February, but the situation got more global attention in April after U.K. health authorities issued an alert about a similar illness. The majority of cases were in children aged 5 and under. That prompted U.S. health officials to issue an alert and to cast a wider net looking at potential cases. They stressed that this investigation is still evolving, and it may turn out that some of these are unrelated.

Now, hepatitis does occur in children, but it's rare. And while U.K. officials say they are seeing more cases than usual, the CDC says, for now, it's not.

SHAPIRO: I mentioned that the cause of the illness is unknown, but do researchers suspect a link to COVID?

GODOY: They're still investigating this, but health officials stress this is definitely not being caused by the COVID vaccine. Most of the children affected are too young to have been vaccinated. As for COVID itself, officials say they aren't aware of these hepatitis cases in kids with COVID, although they are looking for evidence of possible past infection.

SHAPIRO: So what other possible causes are they looking into?

GODOY: Well, hepatitis is usually caused by strains of the hepatitis virus, known as A through E, but all of those have been ruled out. Right now, the leading suspect is a strain of adenovirus. That's a common virus that usually causes mild cold or flu-like symptoms or stomach and intestinal problems. A good number of these children have tested positive for adenoviruses, but there are also other hypotheses being looked at, and it's possible that a combination of factors has left kids more susceptible to getting severely ill when infected with adenovirus - for example, if they'd previously been infected with another virus, including possibly the coronavirus.

SHAPIRO: If parents are concerned about this, what should they be looking out for in their kids?

GODOY: The CDC stresses that severe hepatitis remains rare in children, but it does advise that parents of young children be aware of the symptoms of hepatitis. That includes vomiting, dark urine, stool that's light in color and yellowing of the skin. And of course, if you're at all concerned, contact your pediatrician.

SHAPIRO: That's NPR's Maria Godoy. Thank you.

GODOY: My pleasure. Transcript provided by NPR, Copyright NPR.