DOTHAN, Ala. (WDHN) — The Centers for Disease Control and Prevention is now looking into 5 deaths and 109 cases linked to a mystery virus causing severe liver damage in children. The disease was first seen in Alabama.

CDC’s Deputy Director of Infectious Diseases, Dr. Jay Butler, said during a Friday call that they are investigating cases in 24 states and Puerto Rico.

While medical experts are still stumped as to what this illness might be causing severe hepatitis, they are evaluating several reasons that could be causing the illness.

Overall, 90% of the patients were hospitalized, 14% received a liver transplant, and over half had confirmed adenovirus infections. Medical experts say this is an evolving situation.

States investigating cases: Alabama, Arizona, California, Colorado, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Louisiana, Michigan, Minnesota, Missouri, North Carolina, North Dakota, Nebraska, New York, Ohio, Pennsylvania, Tennessee, Texas, Washington Wisconsin, and Puerto Rico.

Some of the patient’s lab tests identified that they had adenovirus 41, which causes severe stomach illness but is not usually a cause of hepatitis in healthy children.

Laboratory testing has ruled out the hepatitis type A, B, C, and E viruses that usually cause such illnesses. Officials say they are not aware of international travel or other factors that might have put the kids at risk.

They are looking into environmental exposures, medications, or other infections the children may have.

According to the CDC, the COVID-19 vaccine is not the cause of the mystery virus. None of the children in Alabama contracted the COVID-19 virus. They have not ruled out prior COVID-19 infection.

In addition to the U.S., at least 228 cases in 20 countries have been reported, with the U.K investigating the most, with a little over 160 cases.

At this time, medical professionals say it’s important that parents stay up to date on their children’s vaccinations. They also say it’s important to practice good hygiene like washing hands for at least 20 seconds.