An outbreak of acute hepatitis -- an inflammation of the liver -- has killed several children and required liver transplants in others across the globe, according to the World Health Organization. While the cause is undetermined, investigators are studying a family of pathogens, called adenoviruses, that cause a range of illnesses including the common cold.
1. When and where did it start?
Cases were first identified at an Alabama hospital in October 2021, when five children were admitted with liver damage from an unknown cause. Early this year, 10 cases were identified in Scotland. According to the WHO, 348 probable cases had been detected in 20 countries, with another 70 possible cases pending, as of May 10. Most of the probable cases -- 163 -- were in the UK, according to Philippa Easterbrook, a senior scientist at the WHO. The US Centers for Disease Control and Prevention said on May 6 it had 109 under investigation. Only a handful of other countries, including Spain, Israel and Denmark, have reported more than five as of early May. The first cases in Asia were detected in late April in Japan and Singapore.
2. How serious is it?
The CDC reported five deaths among the 109 US cases. Indonesia said in early May that three children there had died. The WHO had reported at least one death on April 23. According to the WHO, affected children were one month to 16 years old, with many age 10 and under. The CDC said of the cases it was investigating, 14% needed a liver transplant.
3. What are the common symptoms?
Abdominal pain, diarrhea and vomiting, followed by jaundice, which is marked by the skin or the whites of the eyes turning yellow. Laboratory tests show signs of severe liver inflammation, with markedly high liver enzyme readings. Most of the children didn’t have a fever. Other symptoms of hepatitis include fatigue, loss of appetite, dark urine, light-colored stools and joint pain.
4. What’s causing it?
A viral organism is likely because the cases are appearing in clusters, according to Tina Tan, a physician at Lurie Children’s Hospital in Chicago and a member of the Infectious Diseases Society of America. Easterbrook said “the leading hypotheses remain those which involve adenovirus.” But experts are awaiting more data.
• According to Easterbrook, around 70% of cases tested were positive for adenovirus, with a specific strain, F type 41, being the most prevalent. (The CDC said about half of the suspected US cases were linked to adenovirus.) The findings are perplexing, however, since adenoviruses normally resolve on their own and don’t cause the severity of disease seen in the children. A study underway in the UK comparing the infection rate with other hospitalized children should help determine whether the adenovirus is just incidental or if a causal link is possible.
• Some children were also infected with the coronavirus that causes Covid-19 -- about 18% of those tested, Easterbrook said, calling a potential role for that virus “an important consideration.” US officials, though, have expressed doubt about any connection with Covid, saying all the patients in the initial Alabama cluster tested negative at the hospital and had no history of previous infection.
• The WHO report also noted the “vast majority” of children affected hadn’t received any vaccine for Covid, making hypotheses about possible side effects from the shots unlikely.
• Common pathogens that cause acute viral hepatitis, including hepatitis viruses A, B, C, D and E, haven’t been found in any of the cases, according to the WHO.
No other risk factors have been identified, including links to international travel, the WHO said. Additional testing for other infections, chemicals and toxins is underway in the affected countries, which have also initiated enhanced surveillance.
5. What’s an adenovirus?
They are common viruses that cause a range of illnesses, including cold-like symptoms, fever, sore throat, bronchitis, pneumonia and diarrhea. There are more than 50 types that can infect humans. While they most commonly cause respiratory symptoms, they can also lead to gastroenteritis, conjunctivitis and bladder infections. Adenovirus type 41 typically causes diarrhea, vomiting, and fever, often accompanied by respiratory symptoms. It isn’t known to cause hepatitis in healthy children.
6. Is this a new disease?
It’s possible that the severe hepatitis is an existing, though rare, result of an adenovirus infection that is being detected more often now thanks to enhanced testing, the WHO said. Adenovirus infections have been on the rise recently after falling to low levels during the Covid pandemic, potentially making young children more susceptible. The possible emergence of a novel adenovirus must also be investigated, the WHO said.
(Updates in sections 1, 2 and 4 with new data from the WHO and CDC)
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