FRIDAY, April 29, 2022 (HealthDay News) -- The origins of a continuing outbreak of acute, potentially lethal hepatitis striking children in countries around the world has experts mystified. But a cluster of recent cases in Alabama all show ties to common viruses, according to a new report from researchers at the U.S. Centers for Disease Control and Prevention.
The official World Health Organization tally of such cases stands at 169 across 11 countries, although media reports suggest the number is now closer to 200.
In these cases, otherwise healthy children have developed the liver disease so severe as to require hospitalization. In the WHO case count, 17 of the children required a liver transplant to survive, and one child died.
The new CDC report hones in on cases in one U.S. state: Alabama.
"In the fall of 2021, clinicians at a children’s hospital in Alabama identified five patients with severe hepatitis and adenovirus infection, including some with acute liver failure," the CDC said in a news release issued on Friday.
"A review of hospital clinical records identified four additional cases, all of whom had liver injury and adenovirus infection," the agency added. "All were previously healthy, ranged in age from about 1 to 6 years old, and had no significant underlying conditions."
Three of the nine patients were so ill that they developed liver failure, and two needed liver transplants, according to the CDC team led by Julia Baker, of the agency's Division of Viral Diseases. All of the children have since recovered.
As was found in many of the cases investigated by WHO, "all nine patients [in Alabama] tested positive for adenovirus," Baker and colleagues reported. Adenoviruses are an extremely common form of virus that can trigger maladies ranging from colds to conjunctivitis and croup.
"Laboratory tests identified that some of these children had adenovirus type 41, which more commonly causes pediatric acute gastroenteritis," the CDC team noted.
Six of the children tested positive the Epstein-Barr virus, but they had no antibodies against this common virus. That "implies an earlier, not active infection," the researchers said.
None of the affected children in Alabama died. However, the Wisconsin Department of Health Services reported this week that four pediatric cases of acute hepatitis had occurred in that state. Tragically, they included "two children who had severe outcomes, one liver transplant and one fatality."
What are warning signs of acute hepatitis in kids? According to the CDC, "prior to hospitalization, most of the children [in Alabama] experienced vomiting and diarrhea, while some experienced upper respiratory symptoms."
Once hospitalized, other symptoms emerged: "Most had yellowing eyes, yellowing skin [or jaundice], and an enlarged liver," the CDC said.
According to the statement from WHO, numerous potential causes for outbreaks in various countries are being investigated. For example, the agency said that "increased susceptibility [to adenoviruses] amongst young children following a lower level of circulation of adenovirus during the COVID-19 pandemic" might be responsible.
Alternatively there's the potential for the "emergence of a novel adenovirus" that might trigger acute hepatitis in kids, along with co-infection with SARS-CoV-2, the virus that causes COVID-19.
One thing that is not to blame: the COVID-19 vaccine.
"Hypotheses related to side effects from the COVID-19 vaccines are currently not supported, as the vast majority of affected children did not receive COVID-19 vaccination," WHO experts pointed out.
The new Alabama findings were reported Friday in the CDC journal Morbidity and Mortality Weekly Report.
Find out more about the acute hepatitis outbreak at the U.S. Centers for Disease Control and Prevention.
SOURCES: World Health Organization statement, April 23, 2022; U.S. Centers for Disease Control and Prevention, statement, April 29, 2022; Wisconsin Department of Health Services, statement, April 27, 2022