ST. LOUIS — Missouri and Illinois are now listed among the 25 states where the Centers for Disease Control and Prevention is investigating severe hepatitis cases among children.

In St. Louis, medical experts at SSM Health Cardinal Glennon Children’s Hospital are keeping a close eye on the outbreak. Doctors said parents should not panic.

The CDC is investigating 109 of these pediatric cases, including five deaths. More than 90% of the children were hospitalized, and a majority of the patients have fully recovered.

More than half of the kids had a confirmed adenovirus infection. However, CDC officials said they don’t know yet if adenovirus is the actual cause.

“Adenovirus is a large family of viruses that commonly cause colds, respiratory infections, pink eye,” said Dr. Jeff Teckman, a SLUCare pediatric gastroenterologist at Cardinal Glennon. “Adenovirus can also infect the intestine and the GI tract. They can make you sick. Unfortunately, we don’t have a vaccine against adenovirus at this time. So yes, even children that are vaccinated in the usual way wouldn’t have specific protection against this virus. We suspect this is the cause of this new issue.”

The symptoms of hepatitis include high fever, abdominal pain, vomiting, diarrhea, and jaundice. The CDC says the hepatitis viruses A, B, C, D and E have not been found in the kids during initial investigations.