You might be wondering how this outbreak could affect your family. Here is what we know so far, based on information from the WHO, CDC and other experts.
What is hepatitis of unknown origin?
Recent cases of hepatitis in young children are being investigated because doctors are not sure what caused it.
Hepatitis means inflammation of the liver. It can affect how well the liver works. In severe cases, it can lead to liver failure.
Hepatitis is often caused by viruses, such as hepatitis A, B, C, D or E. But none of the kids with the unexplained hepatitis tested positive for those viruses.
Hepatitis can also be caused by alcohol or by some medical conditions or medicines. But these causes are unlikely, because the unexplained hepatitis is affecting otherwise healthy children.
And researchers haven't found any links by location or other typical risk factors.
What could be causing it?
Scientists are still working to find out. One possibility is a virus called adenovirus type 41. When CDC investigated a cluster of nine cases in Alabama, they found that several of the children had this virus. The European Centre for Disease Prevention and Control also reported that many children tested positive for adenovirus.
That might be a coincidence. Some children with the hepatitis have not tested positive for adenovirus. And adenoviruses are very common. When you or your kids have symptoms of a cold or stomach flu, it's often an adenovirus. Adenovirus type 41 usually causes symptoms like vomiting, diarrhea and fever. Most people recover on their own at home.
Adenoviruses are not known to cause hepatitis in healthy kids. But they have been known to cause hepatitis in kids with weakened immune systems.
What about COVID-19?
CDC ruled out COVID-19 as a cause of the nine Alabama cases. None of the children there tested positive for the virus that causes COVID-19. And none had any record of ever having the coronavirus. But WHO reported that some of the children in Europe did test positive for COVID-19. And some of the sick kids tested positive for both COVID-19 and adenovirus.
COVID-19 vaccines are not a factor. Most of the kids who have had the unusual hepatitis were not vaccinated.
Who is affected?
This unusual hepatitis is affecting very young children. Most are 6 years old or younger. In the cluster of nine cases in Alabama studied by CDC, the median age was about 3 years.
Is it serious?
Most of the children with the unexplained hepatitis have needed to stay in the hospital. Some have needed liver transplants. And while the disease is very rare and most children who get it recover, some have died.
What are the symptoms?
According to CDC, common signs of hepatitis include:
Loss of appetite.
Jaundice (yellow tinge to the skin and whites of the eyes).
What can parents do?
You can protect your kids from the more common causes of hepatitis by making sure they are up-to-date on their vaccines.
And handwashing is still one of the best ways to avoid viruses of any kind—including adenoviruses. Teach your kids to wash their hands the right way with this five-step infographic.