Outside Europe, Israel (12 cases) and the United States (at least 9) extend the list. Affected children ranged in age from one month to 16 years old, but most were under 10 years old, and many under 5 years old. None of them had comorbidity, but kidney transplants had to be performed on 17 young people. In the UK, one of them lost his life.
A yet unknown evil
Where does this hepatitis come from? “Investigations are continuing in all countries reporting cases. Currently, the exact cause of hepatitis remains unknown,” according to the European Center for Disease Prevention and Control. For now, an infectious cause seems to be considered the most likely, but no common link with contaminated food or a toxicant has been identified.
“You always have to take things seriously” and “watch closely”, but “not fall into psychosis either” because “we don’t even know where it comes from” until then, declared Yazdan Yazdanpanah, chief of the infectious diseases department of the Bichat hospital in Paris and member of the French Scientific Council.
An unusual disease
Hepatitis is an inflammation of the liver, in reaction to viruses, toxins (drugs, poisons, etc.), autoimmune or genetic diseases. Often of benign evolution, its main symptoms – fevers, diarrhoea, stomach pains, jaundice – quickly resolve or remain weak. More rarely, they can lead to kidney failure.
It is the proliferation of causes that challenges specialists. “The growing rise in the number of children with sudden onset hepatitis is unusual and worrying,” Zania Stamataki, from the Center for Liver and Gastrointestinal Research at the University of Birmingham. The fact that certain types of hepatitis affect small children, between 1 and 5 years old, surprises specialists even more, as does the need, in some cases, for a transplant. And the usual viruses that cause acute viral hepatitis (A to E) were not detected in any of the cases, according to the WHO.
Adenovirus, potential but uncertain suspect
Among the leads under study, “adenoviruses” were detected in at least 74 children. Several countries, including Ireland and the Netherlands, have reported increased circulation of these adenoviruses. Fairly common and known viruses, adenoviruses generally cause respiratory symptoms (bronchitis, pharyngitis, etc.), ocular symptoms (conjunctivitis), digestive disorders (gastroenteritis). The majority of humans are infected before they are 5 years old.
But their role in the development of mysterious hepatitis is unclear. If children infected with an adenovirus have suffered from hepatitis in the past, they were immunocompromised children. And adenovirus 41 is not known to cause hepatitis in healthy children, observes the WHO. A new strain of adenovirus could therefore be involved, according to some British scientists. Or other infections and environmental causes could exacerbate adenoviral inflammation.
The possibility of a link with the Covid-19, which is still circulating, is also included in the hypotheses. It was detected in 20 of the children tested. And 19 other children showed co-infection with Covid-19 and an adenovirus. But “if these hepatitises resulted from Covid-19, it would be surprising not to see them distributed more widely given the high circulation of Sars-Cov2”, observed Graham Cooke, specialist in infectious diseases at Imperial College London.