This is a fast moving outbreak that is being updated frequently.

UPDATE: According to the Independent, at least six states across the US have reported either confirmed or suspected instances of a mysterious liver disorder in children also found in countries all over the world. Cases have been confirmed in four states – Delaware, Alabama, North Carolina and Illinois, and officials in New York state and Wisconsin say they are looking into reports of paediatric hepatitis – liver inflammation – that concur with the description issued last week by the Centres for Disease Control and Prevention (CDC). More than 160 cases of liver inflammation have been reported in children without other health problems in around a dozen countries, such as the US, Canada, and Japan, Bloomberg reported.

Cases are aged 1 month to 16 years old. Seventeen children (approximately 10%) have required liver transplantation; at least two deaths have been reported – adenovirus leading cause – some link to COVID-19 infection suspect.

Hilary Brueck  of Insider today added more Hepatitis illnesses to the mystery sickening nearing 200 children worldwide.

Wisconsin health officials reported Wednesday four cases of adenovirus-linked pediatric hepatitis, a type of liver inflammation that can be life-threatening. One of those cases required a liver transplant, and one was fatal, the officials reported. It would be the first known death of a child in the US from the infection that is causing international concern.

Last week, the Centers for Disease Control and Prevention (CDC) issued an alert to healthcare providers nationwide after at least nine suspicious cases of hepatitis were diagnosed in Alabama. Two more were later reported in North Carolina.

The World Health Organization says the same strange illness has also been spreading in Europe, with over 150 children infected, and at least one dead. The highest numbers of cases reported so far have been in the UK and in Spain.

As of April 21, 2022 the WHO reported 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).

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.