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Full Professor of Microbiology, University of Navarra
In the last few weeks, a new increase in cases of severe hepatitis of unknown origin in children between 2 and 6 years of age in several countries. For example, about 4 cases are detected in Scotland every year, but now there are more than 13 cases in a couple of months.
So far, 74 cases have been reported in the UK, 3 in Spain (Madrid, Aragón and Castilla-La Mancha) and some cases are being investigated in Denmark, the Netherlands and the USA (CDC reports 9 suspected cases in the state of Alabama). Possible cases that may have gone unnoticed since October are being reviewed.
Causes and symptoms
Hepatitis is an inflammatory disease affecting the liver. Its cause can be very diverse: infectious (viral or bacterial), immune (autoimmune hepatitis) or toxic (alcohol, toxic substances or drugs).
All children were healthy one week before diagnosis. Symptoms are the usual symptoms of this disease: abdominal pain, vomiting, diarrhea, jaundice (yellowing of the skin and mucous membranes), skin itching, dark urine coloration and poorly pigmented stools.
So far there have been no deaths. Some have recovered, but others have had to be hospitalized and seven have even required liver transplants (one of the Spanish cases).
What hypotheses are being considered?
What is disconcerting is the increase in the number of cases in a very short period of time, their severity and the fact that the cause is not known at this time. There are several possibilities and hypotheses:
Some food, drink or toy poisoning. Toxins or poisons can affect the liver very seriously. At the moment it does not seem likely because no common link has been found between all the cases, but the possibility of an as yet unknown toxin is not ruled out.
It does not seem to be of bacterial origin, it does not present with fever.
None of the children had been vaccinated against covid-19, so this is also ruled out as a possible side effect of the vaccine.
Some, but not all, have tested positive for SARS-CoV-2. One hypothesis would be that coronavirus infection leaves children more vulnerable to other infections. A possible complication or sequela of covid-19 also cannot be ruled out.
However, the hypothesis that seems most likely to some researchers at the moment is an adenovirus infection. Half of the cases have tested positive for these viruses, which normally cause diarrhea, vomiting and cold-like symptoms.
In very rare cases, adenoviruses can cause fulminant hepatitis. It has been suggested that this could be a new, more aggressive adenovirus variant. Another possibility is that it was a common adenovirus but now had a more severe impact on children with a more weakened immune system due to lack of exhibition to other pathogens due to confinement and other measures during the pandemic.
Nor can we rule out that the cause is an as yet unidentified virus.
For the moment, all these cases are available at research. As always, do not panic and act according to health recommendations.