2022-05-20 On cases of unexplained acute hepatitis in children

On cases of unexplained acute hepatitis in children

The Japanese government has started to identify the number of cases of acute hepatitis in children and publishes the results of its investigation in the following article.

At the moment, this hepatitis has not

On cases of unexplained acute hepatitis in children (May 20, 2022)

Every country in the world continues to report cases of acute hepatitis of unknown origin in children.

In order to identify the causes of this acute hepatitis, the World Health Organization (WHO) has established a provisional case definition and asks countries to report cases that meet this definition.

The Ministry of Health, Labor and Social Affairs sent a circular on April 20, 2022, a surveillance alert and requested local governments to provide information on this point. It also sent a circular on April 27 on the follow-up of infected cases that meet these criteria and on active epidemiological investigations.

The cumulative number of cases reported between October 1, 2021 and May 19, 2022 at 10 am that are included in the provisional case definition (※) is published in the annex. We will continue to compile and post the status of case reports on a regular basis.

The Ministry of Health, Labor and Welfare will continue to monitor the infectious situation in other countries and collect information, in cooperation with their governments, the WHO and experts.

We ask the press and all media to pay attention to respect for privacy and not to publish information that allows identifying the affected people or their relatives, etc.


※ The provisional case definition is as follows. “About the occurrence of unexplained hepatitis in children in the United States and Europe (Call for Cooperation) Circular of April 27, 2022, Secretary of Health, Ministry of Health, Labor and Social Affairs.

Hospitalized cases with unexplained hepatitis diagnosed on or after October 1, 2021, which can be classified as follows.

  • 1. Confirmed cases: none at this time.
  • 2. Potential cases: children aged 16 years or younger with acute hepatitis with aspartate transaminase (AST) or alanine transaminase (ALT) > 500 IU/L, and in whom the involvement of the hepatitis A to E virus has been ruled out.
  • 3. Epidemiologically relevant cases: people of any age with acute hepatitis who are contacts of potential cases.

Information (appendix summaries)

The government records a total of 24 cases between October 2021 and May 19, 2022. All are in the category of “potential cases.” Among them,

  • 2 tested positive for COVID-19
  • 2 tested positive for adenovirus. it should be noted that
    • The two cases of adenovirus are not the same type as those found in Britain.
    • Another 7 cases handled in the regional health research centers await the results of additional tests.

Because the study is done retroactively, some of these cases have already been discharged from the hospital and are feeling better. Therefore, all these cases do not necessarily date back to April and are not related to this recent epidemic.

About acute hepatitis

Acute hepatitis is diagnosed when patients have no symptoms or have loss of appetite, malaise, nausea/vomiting, right upper quadrant pain, dark urine, diarrhoea, etc. and for those with jaundice.

In the Liver Transplantation Case Registry Report of the Japan Liver Transplantation Society, acute liver failure is classified into HBV, drug-induced hepatitis, autoimmune hepatitis, viral hepatitis (non-HBV), hepatitis of unknown cause, etc.

There were 41 liver transplants in pediatric care between 2018 and 2020. These were aimed at treating

  • 2 viral hepatitis (not HBV),
  • 36 hepatitis of unknown cause,
  • 1 neonatal hemochromatosis,
  • 2 other types of hepatitis.

The cause of acute hepatitis varies depending on the virus. The virus can be transmitted by mouth, by blood, during mother-to-child transmission, sexually, etc.

For all these types of hepatitis, only treatment of the symptoms is done. However, in the case of fulminant hepatitis, special treatment may be necessary, such as plasmapheresis or adjuvant treatment with an artificial liver and liver transplantation.

Source:  (mhlw.go.jp)

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