Cases of Mysterious Hepatitis Identified in American Kids

A white child hugging a teddy bear looking sad in a hospital bed.


Key Takeaways

  • Several clusters of severe acute hepatitis in children have been occurring worldwide since last fall.
  • Experts believe the cases are likely linked to an adenovirus, a group of common viruses that cause illnesses like the flu and the common cold.
  • As of the beginning of May, cases in the United States have been reported in Alabama, Illinois, North Carolina, and Wisconsin.

On April 21, 2022, the Centers for Disease Control and Prevention (CDC) issued a nationwide medical alert after children in four states were diagnosed with severe hepatitis.

The cause of the illness is still unknown, leaving healthcare professionals confused about why otherwise healthy children are developing serious liver disease.

The new cases of hepatitis in American kids are far from the first to be reported. Early warnings of mysterious clusters of hepatitis cases in kids started coming from Europe last fall.

As of early May, the World Health Organization (WHO) has reported 169 cases worldwide, with 17 children requiring a liver transplant, and one case resulting in a child’s death.

In the United States, five states have reported a total of 25 cases in children as of April 29.

Nine children in Alabama, all under the age of 6, developed severe inflammation of the liver (hepatitis). Three children developed acute liver failure and two needed liver transplants.

Cases have also been reported in California, Illinois, North Carolina, and Wisconsin.

What Is Hepatitis?

Hepatitis is inflammation of the liver that’s caused by a virus or another medical condition.

People can develop hepatitis from:

Viral hepatitis is the most common type of hepatitis in the U.S. There are five viruses typically associated with hepatitis:

  • Hepatitis A: This type is linked to contaminated food and water. It can also be spread through oral-anal sex. It usually does not cause life-long illness, and there is a vaccine available for it.
  • Hepatitis B: This type is linked to contaminated blood and bodily fluids. It is usually spread through sex and is considered a sexually transmitted infection (STI). There is a vaccine available for it.
  • Hepatitis C: Is linked to contaminated blood (e.g., needles, blood transfusions). If it’s not treated, it can become a chronic infection. There is no vaccine available for it.
  • Hepatitis D: Is linked to contaminated blood or bodily fluids but can only be contracted by a person that already has hepatitis B, therefore, getting vaccinated against hepatitis B can help prevent it.
  • Hepatitis E: Linked to contaminated food or water but can be spread through the oral-anal route as well. It is rare in the U.S. and there is no vaccine.

It’s not uncommon for kids to be infected with a hepatitis virus, but most do not have symptoms (asymptomatic) or only have mild illnesses—especially if they are young and healthy.

Vaccinations for hepatitis A and B have added a layer of protection for children who might be exposed. These vaccines were added to the national immunization schedule in 1980 and 1995, respectively. There is currently no vaccine for hepatitis C, D, or E.

A Possible Viral Link

The three most common types of viral hepatitis have been ruled out in the new cases of hepatitis in children.

Global public health investigators have started looking for what else the children might have had in common. One thing they looked for right away was infections.

While the children have tested positive for various viruses—including Epstein-Barr virus, rhinovirus, respiratory syncytial virus, and COVID-19—one virus seemed to be more common among them than the others.

At least 74 of the children with hepatitis have tested positive for a common adenovirus.

What Is Adenovirus?

Adenoviruses are common viruses that cause mild illnesses, with symptoms similar to the flu or the common cold.

However, for people with a weakened immune system or underlying medical conditions, the virus can lead to serious symptoms that may require hospitalization.

Symptoms of adenovirus infection typically include:

  • Fever
  • Sore throat
  • Cough
  • Vomiting and diarrhea 
  • Acute bronchitis (inflammation of the lungs)
  • Pneumonia (lung infection)
  • Pink eye” (viral conjunctivitis)

Leina Alrabadi, MD, a pediatric gastroenterologist and hepatologist with Stanford Children’s Health, told Verywell that adenoviruses “can cause short-lived hepatitis, but it usually does not progress to liver failure. It is uncommon for this to occur with adenovirus, which is why doctors are keeping a close eye on this worldwide.”

One of those viruses—adenovirus 41—is known to be connected to inflammation of the stomach or intestines (acute gastroenteritis). It’s also known to cause hepatitis in children with weak immune systems. However, most of the children in the recent cluster of cases were generally healthy.

Leina Alrabadi, MD

It is uncommon for this to occur with adenovirus, which is why doctors are keeping a close eye on this worldwide.

— Leina Alrabadi, MD

In light of the findings, the CDC has requested that providers screen children with hepatitis of unknown origin for adenovirus and report the results to the CDC as well as state public health departments.

While children are protected from some viruses that cause hepatitis through immunization, there is no vaccine that protects against hepatitis from an adenovirus.

What’s more, even though adenovirus can cause hepatitis, adenovirus 41 has not been linked to severe hepatitis cases in the past. 

“Experts are trying to understand this season’s adenovirus and why otherwise healthy children are getting sick from it,” said Alrabadi. “Adenovirus is not a new virus, but a virus we’ve always known about.”

What Caregivers Should Know

Severe hepatitis in children is uncommon, and experts say that caregivers don’t need to be alarmed by the recent spike in cases. That said, there are some key points for adults caring for children to keep in mind.

Signs and Symptoms of Hepatitis

If your child comes down with a cold or flu and starts having symptoms of acute hepatitis, contact their pediatrician right away.

Symptoms of acute hepatitis to watch for include:


Telling caregivers not to worry about their children is rarely enough to reassure them. If you’re caring for a child and worried about the unexplained cases of hepatitis—especially if they have appeared in your community—know that there are some steps you can take to protect your family.

Adenovirus is contagious; it easily spreads through coughing, sneezing, and close contact with infected people.

Alrabadi said that in general, “good hygiene and proper hand washing is essential in preventing transmission of disease, including viral illnesses which can cause acute hepatitis.”

As you would to avoid other infectious illnesses, make sure that you:

  • Wash your hands properly and frequently
  • Cough and sneeze into your elbow
  • Disinfect commonly used surfaces in your home
  • Avoid close contact with people that are sick
  • Wear a face mask in public areas

What This Means For You

Caregivers do need to be concerned about the spike in hepatitis cases in kids, however, let your pediatrician know if your child is showing signs of acute hepatitis, such as yellowing of skin/eyes, dark urine, and light-colored stools.

Since hepatitis vaccines don’t protect against the adenovirus, the best way to stop the spread of the virus is to wash your hands, cough and sneeze into your elbow, and stay away from people who are sick.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. CDC alerts providers to hepatitis cases of unknown origin.

  2. World Health Organization. Multi-country – acute, severe hepatitis of unknown origin in children.

  3. Baker JM, Buchfellner M, Britt W, et al. Acute hepatitis and adenovirus infection among children — Alabama, October 2021–February 2022MMWR Morb Mortal Wkly Rep. 2022;71(18). doi:10.15585/mmwr.mm7118e1

  4. Johns Hopkins Medicine. Hepatitis.

  5. Centers for Disease Control and Prevention. What is viral hepatitis?.

  6. Children’s Hospital of Philadelphia. Vaccine history: developments by year.

  7. Centers for Disease Control and Prevention. Adenovirus VIS.

  8. University of Alabama at Birmingham. New adenovirus strain potentially linked to pediatric hepatitis outbreak in Alabama.

By Amy Isler, RN, MSN, CSN
Amy Isler, RN, MSN, CSN, is a registered nurse with over six years of patient experience. She is a credentialed school nurse in California.