About two dozen states reported suspected cases after the Centers for Disease Control and Prevention put out a call for doctors to be on the lookout for surprising cases of hepatitis. The cases date back to late October in children under 10. So far, only nine cases in Alabama have been confirmed.
"We are casting a wide net to broaden our understanding," the CDC’s Dr. Jay Butler said Friday.
Butler explained that though the CDC is "casting a wide net" in its investigation, not all of the cases may be linked to the same cause.
"Investigators both here and across the globe are hard at work to determine the cause," Butler continued.
What's causing the illnesses isn't clear. Adenovirus was detected in half the children, "but we do not know if it is the cause," he said.
There are dozens of adenoviruses, many of them associated with coldlike symptoms, fever, sore throat and pink eye. But some versions can trigger other problems, including inflammation in the stomach and intestines. Officials are exploring a link to one particular version that’s normally associated with gut inflammation.
The Centers for Disease Control and Prevention said in a press briefing that the infections across 25 states may be connected to a global outbreak of the disease that has killed multiple children. This week, there have been 300 probable cases in 20 countries, according to the World Health Organization.
In the U.S., 94% of the children were hospitalized and eight received liver transplants.
"It’s still a very rare occurrence," Butler said. "A majority of these cases have recovered and recovered fully."
In April, the CDC issued a health advisory in response to the cluster of mysterious hepatitis cases in Alabama involving nine children.
The mystery goes back to November, when Alabama health officials began looking into the first of nine cases of severe hepatitis in children in that state. None tested positive for the viruses that commonly cause hepatitis. However, testing was positive for adenovirus.
Butler said none of the Alabama children were vaccinated against COVID-19. That has been ruled out as a possible cause, "and we hope this information helps clarify some speculation circulating online."
Symptoms of hepatitis include inflammation of the liver, fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, dark urine, light-colored stools, joint pain, and jaundice.
In addition to Alabama, the states reporting suspected cases: 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. Puerto Rico also reported at least one case.
The Associated Press contributed to this report