NewsDesk @bactiman63

This weekend, the World Health Organization (WHO) published an outbreak overview of the acute, severe hepatitis of unknown origin in children.

Here is some of that information:

As of 21 April 2022, at least 169 cases of acute hepatitis of unknown origin have been reported from 11 countries in the WHO European Region and one country in the WHO Region of the Americas. Cases have been reported in the United Kingdom of Great Britain and Northern Ireland (the United Kingdom) (114), Spain (13), Israel (12), the United States of America (9), Denmark (6), Ireland (<5), The Netherlands (4), Italy (4), Norway (2), France (2), Romania (1), and Belgium (1).

Cases are aged 1 month to 16 years old. Seventeen children (approximately 10%) have required liver transplantation; at least one death has been reported.

The clinical syndrome among identified cases is acute hepatitis (liver inflammation) with markedly elevated liver enzymes. Many cases reported gastrointestinal symptoms including abdominal pain, diarrhoea and vomiting preceding presentation with severe acute hepatitis, and increased levels of liver enzymes (aspartate transaminase (AST) or alanine aminotransaminase (ALT) greater the 500 IU/L) and jaundice. Most cases did not have a fever. The common viruses that cause acute viral hepatitis (hepatitis viruses A, B, C, D and E) have not been detected in any of these cases.  International travel or links to other countries based on the currently available information have not been identified as factors.

Adenovirus has been detected in at least 74 cases, and of the number of cases with information on molecular testing, 18 have been identified as F type 41. SARS-CoV-2 was identified in 20 cases of those that were tested. Furthermore, 19 were detected with a SARS-CoV-2 and adenovirus co-infection.

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While adenovirus is currently one hypothesis as the underlying cause, it does not fully explain the severity of the clinical picture. Infection with adenovirus type 41, the implicated adenovirus type, has not previously been linked to such a clinical presentation. Adenoviruses are common pathogens that usually cause self-limited infections. They spread from person-to-person and most commonly cause respiratory illness, but depending on the type, can also cause other illnesses such as gastroenteritis (inflammation of the stomach or intestines), conjunctivitis (pink eye), and cystitis (bladder infection). There are more than 50 types of immunologically distinct adenoviruses that can cause infections in humans. Adenovirus type 41 typically presents as diarrhea, vomiting, and fever, often accompanied by respiratory symptoms. While there have been case reports of hepatitis in immunocompromised children with adenovirus infection, adenovirus type 41 is not known to be a cause of hepatitis in otherwise healthy children.

Factors such as increased susceptibility amongst young children following a lower level of circulation of adenovirus during the COVID-19 pandemic, the potential emergence of a novel adenovirus, as well as SARS-CoV-2 co-infection, need to be further investigated. Hypotheses related to side effects from the COVID-19 vaccines are currently not supported as the vast majority of affected children did not receive COVID-19 vaccination. Other infectious and non-infectious explanations need to be excluded to fully assess and manage the risk.