(ABC4) – The Centers of Disease Control and Prevention (CDC) recently held a media briefing to discuss an ongoing investigation of an outbreak of acute hepatitis with an unknown cause in children that’s taking place both nationally and internationally.

It is important to note the young age of the patients being investigated, who averaged around two years old.

As mentioned in the briefing, the CDC issued a nationwide health alert on April 21 to notify clinicians and public health authorities about the initial investigation which involved nine children at the time in Alabama who were identified from Oct. 2021 to Jan. 2022 with hepatitis and adenovirus infection.

All nine patients were previously healthy, came from different parts of the state, had no previous or current diagnosis of COVID-19, had not received a COVID-19 vaccine, and eventually were hospitalized with significant liver injury with no known cause, some with acute liver failure.

Additionally, among the nine patients, lab tests found that some had adenovirus type 41, which usually presents as a stomach illness. However, none of these children experienced underlying conditions which are commonly seen in this type of adenovirus. This strain of the disease most often occurs in immunocompromised patients and is not a known cause of hepatitis in otherwise healthy children.

In the media briefing that took place on May 6, Jay Butler, M.D., Deputy Director for Infectious Diseases, stated that officials are now investigating 109 children with hepatitis of unknown cause occurring in 25 states and territories over the past seven month throughout America. So far, five patients have died.

According to the CDC, 90% of the patients being investigated were hospitalized, while 14% received liver transplants, and over half have a confirmed adenovirus infection.

At this time, experts are looking into what role adenovirus might play in causing the illness. As noted by Dr. Butler, experts have not yet determined whether adenovirus is the cause of the illness or if the liver inflammation was caused by an immune response to it. Other factors, such as possible drugs, toxins, and environmental exposures are being considered as well as possible causes.

Among other things, officials are additionally examining if similar cases that may have been overlooked could have been occurring at a less severe level for some years now. Cases like these would have been made more distinguishable this year by the reduced number of infections which emphasize clusters as a result of the nations COVID-19 prevention efforts.

Outside of America, Umesh Parashar, M.D., Chief, Viral Gastroenteritis Branch, Division of Viral Diseases, disclosed that more than 160 cases are being investigated in the U.K. alone, adding that globally, there are “clearly” more than 200 cases outside of the U.S.

Though it will take time for public health experts to assess the cases and learn more, Dr. Butler notes that it is important for parents and clinicians to help out in the ways they can. According to Butler, parents should watch for signs of liver distress in their young children, including nausea, vomiting, yellow skin and eyes, dark urine, and light stool. Additionally, it is important to ensure your children are up-to-date on vaccines.