Hepatitis in children: what are adenoviruses

Health authorities around the world are working to clarify the causes of the increase in cases of fulminant hepatitis in previously healthy children, registered in different parts of the world. As of April 21, 2022, there were 169 cases in 12 countries (including Italy), 114 in the United Kingdom alone, mostly in patients under 10 years of age.

The outlines of the story are still uncertain – the WHO itself reports that “it is not clear whether there has been an increase in hepatitis cases or an increase of awareness of cases of hepatitis that occur with an expected frequency but which are usually not noticed “. Currently one of the possible suspected causes is an infection with adenovirusthe pathogen most commonly found in children in which thorough testing has been done.

Out of the blue. The cases concern infants, children and young people from one month to 16 years of age. About 10% of them needed a liver transplant, and although the infection has resolved favorably in most cases, at least one death has occurred so far. Doctors are puzzled by the severity of the disease, which occurs in otherwise healthy children with no immune system problems.

For hepatitis we mean inflammation of the liver usually resulting from a viral infection, which can depend on genetic factors, exposure to environmental or toxic chemicals, alcohol and drugs. In children, fulminant hepatitis is possible but very rare. Since the information collected so far has not highlighted any relationships with the foods consumed, habits and place of origin of the young patients, we are more likely to suspect a viral infection. However, none of the children were found to be positive for the viruses that cause the five main types of hepatitis (A, B, C, D, E), some of which are protected with vaccines.

Adenoviruses: what they are. Adenoviruses are DNA viruses that are widespread in humans and especially in children. They generally cause mild, typically respiratory symptoms (laryngitis, tonsillitis, cough), at other times they cause conjunctivitis, gastrointestinal disturbances or cystitis. The adenovirus most found so far in detailed cases, isolated in at least 74 patients, is an adenovirus of subtype 41, usually responsible for a mild gastrointestinal flu with nausea, vomiting, diarrhea and abdominal pain.

The infection usually clears up in a week or two. In immunocompromised children, this adenovirus can cause hepatitis, but it is a very rare complication. This is why the presence of adenovirus in children’s blood alone is not enough to explain the severity of symptoms, the apparently higher number of cases and the occurrence in healthy children, without previous health problems.

Until now adenovirus 41 had never been associated, in healthy people, with the typical clinical picture of these hepatitis – which in addition to the classic gastrointestinal symptoms presented jaundice (yellow color of the eyes and skin), enlarged liver and transaminases (enzymes that increase in concentration when liver cells break down) out of control.

What is being worked on. According to the European Center for Disease Prevention and Control, ‘the currently most plausible hypothesis is that a cofactor affecting children who are having an adenovirus infection, which would be mild under normal circumstances, triggers a more serious infection. or immune-mediated liver damage ‘.

We are trying to understand if there have been, in the genome of the virus, mutations which can make liver inflammation easier and more frequent. Another hypothesis is that the restrictions imposed by the covid pandemic have limited the exposure of children to adenoviruses at an early age, and that now the encounter with the pathogens takes place a little later and more aggressively.

Furthermore, the concomitance between adenovirus infections is investigated and the cases of covid now ubiquitous even in children: in most cases, children had not been vaccinated against SARS-CoV-2 (the covid coronavirus), and in the USA it has been estimated that 75% of under 17s have now contracted covid . However, a recent US CDC report on 9 children affected by the mysterious hepatitis in Alabama appears to have ruled out adenovirus and SARS-CoV-2 coinfections.

A connection, hastily hypothesized by some on the Net, with anti-covid vaccines is also excluded: even if some vaccines (in Italy AstraZeneca and Janssen) use inactivated adenoviruses as vectors to deliver the information to the body to produce the spike protein, these vectors have been genetically modified so that they are unable to proliferate or result in infections.

What can we do? While trying to find out more, doctors recommend paying attention to hand hygiene, as is now customary in the era of covid, and to monitor the possible occurrence of these symptoms at the same time: dark urine, light stools, yellowish color of the eyes, muscle aches, loss of appetite, in children with symptoms of a gastrointestinal flu.

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