The mystery of the cases of pediatric hepatitis that occurred in several countries last spring, at least 1,000, which led to 22 deaths and 50 liver transplants has been revealed: the cause could have been a mix of viral co-infections led by a virus itself non-pathogenic, the so-called adeno-associated virus 2 (AAV2), but aided by common cold and fever viruses. It is the result of three independent studies, conducted between the United States and Great Britain, by the University of San Francisco, the University of Glasgow and University College London, all published in the journal Nature.
Adeno-associated viruses (AAVs) are a small group of viruses, so called because they were first isolated with adenoviruses; by themselves they cannot cause a productive infection (that is, with replication of the viral DNA, assembly of new viruses and infection of other cells), to do so they need co-infecting helper viruses, such as adenoviruses.
US experts conducted genomic analyzes of blood, nasal swab and stool samples from 16 pediatric cases. Samples were compared to 113 control samples.
In the blood of the young patients, adeno-associated virus 2 (AAV2) was detected in 93% of cases and human adenoviruses (HAdV) were found in all cases; a specific type of adenovirus linked to gastroenteritis (HAdV-41) was found in 11 cases. Additional Epstein-Barr, herpes, and enterovirus co-infections were found in 85.7% of cases. The results mirror those of the other two studies conducted in the UK. All three studies identified co-infections from multiple viruses, and 75% of children in the US study had three or four viral infections concurrently.
Because AAVs are not considered pathogenic per se, it has not yet been established whether they are the direct cause of severe acute hepatitis. The study notes, however, that children may be particularly vulnerable to more severe hepatitis triggered by co-infections, with the peak typically being between 1 and 5 years, and the median age of affected children in the study was 3 years.
The best way to protect children from this unlikely outcome is to wash their hands frequently and stay home when they are sick to avoid the risk of co-infections, the authors conclude.
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