The Centers for Disease Control and Prevention issued a nationwide health alert on Wednesday, urging doctors and health officials to keep an eye out for any similar cases after a cluster of severe hepatitis cases in Alabama children.

Officials are looking into the possibility that an adenoviruses, one of a group of common viruses that can cause cold-like symptoms, may be to blame.

There are a wide range of causes for the inflammation of the liver, including viruses, chemical exposures, some medications and other medical conditions.

The Alabama Department of Public Health has recorded nine unexplained cases of hepatitis in otherwise healthy children under the age of 10. None of the children died, but a few developed serious health problems.

Nine children tested positive for adenoviruses. A number of people were determined to have adenoviruses type 41, which can cause vomiting and respiratory symptoms.

It is known that adenoviruses can cause hepatitis in children.

It is not typical for it to cause full-on liver failure in healthy kids.

The C.D.C. said in a statement on Thursday that it had ruled out some common causes of inflammation in the Alabama cases.

At this time, we believe adenoviruses may be the cause for these reported cases, but investigators are still learning more.

Similar cases have been reported in Britain.

There are many questions about the rare cases of the disease.

It is important not to panic, said Dr. Richard Malley, an infectious disease doctor at Boston Children's Hospital.

A cluster of cases, especially among this age group, is definitely something to monitor closely, according to an epidemiologist at the University of Alabama.

It is possible that an adenoviruses is the cause, but it is not certain. Doctors said that adenoviruses are common in children, and that the children may have been exposed to the virus incidentally.

Experts said there was no clear connection between the coronaviruses and Covid-19. The Alabama children did not have Covid, even though several of the British children had it.

He said that a connection to the coronaviruses could not be completely ruled out.

The agency wants health care providers to test children with unexplained hepatitis for adenoviruses and to report those cases to health officials.

The child's doctor should be contacted if the child shows signs of serious hepatitis, such as a yellow skin and eyes, and abdominal pain. He said that even serious cases of the disease can be treated.

The same strategies that many families have used to reduce the risk of Covid will be useful if the cases have a viral cause.

The things they learned about how to keep their kids safe from Covid will help keep their kids safe from other viruses.