UNDERSTAND IT ALL – Why do the cases of acute hepatitis detected in children worry scientists?

More than 169 cases of acute hepatitis have been detected over the past few weeks in around ten European countries. Experts wonder about this inflammation of the liver, the origin of which remains unknown.

The phenomenon is spreading and worrying. More than 169 cases of acute hepatitis affecting children have been detected across ten European countries since mid-April. The seriousness of the cases, some requiring a liver transplant, as well as the still unknown origin of this form of severe inflammation, are worrying scientists and the World Health Organization (WHO).

• What do we know about the detected cases?

The alert was launched on April 15 in a note from the WHO, indicating that 74 cases of hepatitis of unknown origin had been detected in Great Britain and Northern Ireland.

The health organization already specifies that given “the increase in cases reported over the past month and the increase in case-finding activities, more cases are likely to be discovered in the following months”.

Since then, at least 169 cases of acute hepatitis have been detected in ten countries, the majority of which in the United Kingdom (114 cases), according to the WHO. Other European countries are also concerned: Spain (13 cases), Denmark (6), Ireland (less than 5), the Netherlands (4), Italy (4), Norway ( 2), Romania (1), Belgium (1). France is also concerned with 2 cases, as well as two non-European countries: Israel (12 cases) and the United States (at least 9 cases).

Affected individuals ranged in age from one month to 16 years, with a majority of children under 10 years old and many under 5 years old.

• How does the disease manifest?

According to the WHO, patients with this severe inflammation of the liver usually first presented with gastrointestinal symptoms, such as abdominal pain, diarrhoea, vomiting and the onset of jaundice, before seeing especially their liver enzyme levels go up. Most did not have a fever.

Many patients had to be hospitalized and in total, 17 patients had to benefit from a liver transplant and one of them died.

• Why is this hepatitis worrying?

The fact that this hepatitis adopts an unknown form and that it affects very young children are the main concerns of experts. According to the WHO, hepatitis does not fit the description of hepatitis types A, B, C, D and E on the basis of symptoms. The viruses that usually cause hepatitis have not been detected in the patients.

The steady increase in the number of detected cases is also of concern to scientists. “The growing rise in the number of children with sudden onset hepatitis is unusual and worrying,” Zania Stamataki, of the University of Birmingham.

The disease also remains of unknown origin for the moment, even if “investigations are continuing” in this direction, according to the European Center for Disease Prevention and Control (ECDC).

• What are the possible causes?

Among the avenues under study, the experts are particularly focusing on that of adenoviruses, detected in at least 74 children so far, including 18 cases of “type 41” adenovirus, and which are actively circulating in Ireland and the -Low.

These viruses, considered fairly common and well known to scientists, are transmitted by the faecal-oral or respiratory route and generally cause mild infections such as bronchitis, conjunctivitis or gastroenteritis.

The role of adenoviruses in the development of mysterious hepatitis, however, remains unclear, as adenovirus 41 is not known to cause hepatitis in healthy children, according to the WHO. A new strain of adenovirus could therefore be involved, according to some British scientists, like other infections and environmental causes.

• Is there a link with Covid?

The link between hepatitis and Covid-19 is one of the hypotheses considered by scientists, while the virus was detected in 20 of the children tested and 19 other children showed co-infection with Covid and an adenovirus.

But “if these hepatitises resulted from Covid, 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, with Science Media Center.

After more than two years of pandemic and barrier gestures, the question of an immune “debt” which would make certain children more fragile is also raised by certain scientists, without certainty. A possible role of anti-Covid vaccines, on the other hand, has been ruled out, a large majority of children were not vaccinated, according to the WHO.

Pending more knowledge on the subject, the WHO indicates that regular hand washing and wearing a mask can prevent adenovirus contamination and other common infections.

Juliette Desmonceaux with AFP

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