Mystery child hepatitis cases linked to previously 'harmless' virus

The person is Michael Le Page.

The adeno-associated virus 2 has been found in almost all of the children in the two independent studies. The immune response of almost all the children with hepatitis is affected by their genes.

It wasn't previously thought to cause any disease, but the adeno-associated virus 2, or AAV2, is a common virus that has been around for a long time. The virus can stay in the body indefinitely if it integrates its genes into the cells' genomes.

It's unusual that AAV2 can only replicate in the presence of other viruses such as an adenoviruses. It's not clear if AAV2 is the cause of the hepatitis or if it's just an indicator of an adenoviruses.

The findings suggest that children with a genetic susceptibility to AAV2 may be at increased risk of developing a serious disease.

A lot more work is needed to prove that there is an immune-mediated cause of the disease.

She thinks that a number of these cases have been unrecognized for a long time. In Scotland, there were lower than usual numbers of adenoviruses infections due to covid-19 restrictions, followed by a big peak in adenoviruses infections once the measures were relaxed.

We are just seeing everything at once, and we don't think the lock down caused this.

In April of this year, doctors in Scotland reported a cluster of cases of young children with damage to the bile duct that wasn't caused by the hepatitis viruses. According to Antonia Ho, a researcher at the University of Glasgow, the children initially had gastrointestinal symptoms such as diarrhoea.

There are more than 1000 cases of unknown cause in children around the world. There have been 22 deaths of children so far.

Ho says the true numbers could be bigger. Many countries don't test for the hepatitisviruses and can't identify cases that aren't caused by them

In order to find the cause, Ho, Thomson and their colleagues took blood samples from children with and without adenoviruses, as well as healthy children of the same age and age group. None of the children with the same disease had AAV2 in their system. The AAV2 was present in four of the nine children.

The team found that eight of the nine children have a variation in the genes that can affect the immune response to infections. Only 16 percent of people in Scotland have this variant.

A team led by Judith Breuer at the Great Ormond Street Institute of Child Health in London compared children with the same disease. Only 27 of the 28 children had AAV2 in their blood, and only at very low levels.

The team couldn't find viral particles with an electron microscope, but they did find AAV2 RNA. The suggestion is that there is an indirect viral mechanism.

Thomson thinks it's unlikely that the coronaviruses can play a role in the development of these diseases. The affected children were not more likely to have had covid-19 than the other children.

There is a decline in the number of cases in children. Larger studies will need to be done to confirm the findings and work out the underlying mechanism.

It is too early to talk about treatments.