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A mysterious global epidemic of hepatitis affecting children in 35 countries has spread in 2022. If its reason was until now unknown, a set of new studies tells us that a co-infection could be to blame.
We now know a little more about the mysterious epidemic of acute hepatitis which raged in 2022 among young children in Europe, particularly in the United Kingdom but also in France. In a few months, several hundred cases of acute hepatitis had indeed been reported in healthy children suddenly suffering from jaundice, diarrhea and vomiting and abdominal pain. More than 1,000 probable cases had been reported in 35 countries, according to the World Health Organization. About 5% of the children needed a liver transplant and 2% died.
A new report of 3 studies (American, English and Scottish) published in the journal Nature is now providing the beginning of a response, targeting in particular the adeno-associated virus type 2 (AAV2).
The track of a privileged co-infection
This virus was indeed found at high levels in 93% of children affected in the United States, 81% in Scotland and 96.4% in England. However, if this virus is rather harmless when it is alone, fought by the immune system of the child, it would manage to replicate in the cells of the liver, when one or more other viruses are encountered by the child.
Is this the case in this epidemic? Possible, answer the three studies: Epstein-Barr viruses or human herpes viruses (HHV-6B) were thus detected by PCR test in 13 out of 14 American children. herpes and adenoviruses were weak but present.
In all the children studied in Scotland, the researchers also identified a gene involved in the identification of infected cells by the immune system, which would constitute a risk factor for the onset of acute hepatitis.
Covid, another sensitivity factor?
The fact that the same result appears in three separate studies supports the proposed explanation. However, other factors may also come into play. The timing of the outbreak may also have been linked to the relaxation of pandemic precautions, leaving large numbers of young children exposed to common viruses they had not previously encountered. “This may have resulted in a population that is very vulnerable to infection with multiple viral infections,” said Dr Charles Chiu, an infectious disease specialist and microbiologist at the University of California, San Francisco, and author of the new US study.
Another explanation is that, in a small subset of children, infection with multiple viruses may have triggered an overly strong immune response, which damages the liver.
The results are therefore not definitive and many uncertainties remain, in particular on the way in which these infections could trigger hepatitis and whether AAV2 is the cause of this liver damage or is simply associated with it, without a causal link. “Further research is also needed to determine if one or more of these viruses directly damage the liver.”said the author.