People walk into the Children's Hospital of Georgia in Augusta, Georgia, U.S., January 14, 2022.
People walk into the Children's Hospital of Georgia in Augusta, Georgia, U.S., January 14, 2022. Reuters / HANNAH BEIER

U.S. health officials on Friday said they are investigating 109 cases of severe hepatitis of unknown origin in children, including five reported deaths, updating a nationwide alert issued in April for doctors to be on the lookout for such cases of the liver disease.

The cases have been identified over the past seven months in 25 states and territories, Dr. Jay Butler, deputy director for infectious diseases at the U.S. Centers for Disease Control and Prevention (CDC) said during a conference call.

He said around half of the 109 children diagnosed with hepatitis were also infected with a type of adenovirus, a virus that causes the common cold, but the agency is still investigating the exact cause of the illness.

The update follows investigations in the United States and Europe of clusters of hepatitis in young children. The CDC said it is working with counterparts in Europe to understand the cause of the infections that can cause liver damage and lead to liver failure.