Japan Reports First Death From Acute Hepatitis of Unknown Origin

A replica of the hepatitis virus on display as part of an awareness event in Mumbai, India, on July 28, 2014. Punit Paranjpe/AFP via Getty Images

Japan has confirmed its first death from unexplained acute hepatitis, a disease involving liver inflammation that has affected children in many countries, according to local reports on April 3.

The Japanese health ministry did not provide further details about the case, nor did it reveal the age of the deceased patient.

The Japan Society for Pediatric Hepatology said it would launch an investigation to determine the patient’s symptoms and the underlying cause of the illness, NHK reported.

The ministry said there may have been more deaths related to the illness in Japan, but they had not been disclosed out of respect for “personal information,” according to Japanese media Asahi Shimbun.

Data released by the ministry showed that at least 162 cases of acute hepatitis had been identified in the country as of March 17, with three of those cases requiring liver transplants, the report stated.

The patients were aged between 16 months and nine years and two months, many of whom experienced gastrointestinal symptoms, including fever, stomach pain, diarrhea, and vomiting, according to NHK’s report.

The cause of acute hepatitis is unknown. Meanwhile, Greece reported its first baby death from acute hepatitis in July last year.

Acute Hepatitis Linked to Coronavirus

The World Health Organization (WHO) said in a July 2022 statement that it had received reports of 1,010 probable cases of acute hepatitis in children from 35 countries, including 22 deaths.

Nearly half of the reported cases were in Europe, with 272 cases from the United Kingdom alone. Of the 435 cases reported in the Americas overall, 334 cases were recorded in the United States.

WHO said that laboratory tests conducted on the affected children did not indicate the presence of hepatitis A to E.

Other pathogens like adenovirus and the coronavirus were detected “in a number of the cases,” but the data is incomplete, the health agency stated.

“Adenovirus continues to be the most frequently detected pathogen among cases with available data,” WHO said. “SARS-CoV-2 has been detected in a number of cases, however, data on serology results are limited.”

Adenovirus is a common virus that can cause a wide range of illnesses, such as colds, fever, sore throats, and pneumonia.

A firefighter from the Marseille Naval Fire Battalion administers a nasal swab to a child at a testing site for COVID-19 in Marseille, France, on Sept. 17, 2020. Eric Gaillard/Reuters

According to a report posted last year on medRxiv, which has yet to be peer-reviewed, children with COVID-19 are at significantly increased risk for liver dysfunction afterward.

A separate team of researchers suggests in The Lancet Gastroenterology & Hepatology that it’s possible the affected children, many of whom are too young to be vaccinated, may have had mild or asymptomatic COVID-19 infections that went unnoticed.

A theory put forward by the researchers is that lingering particles of the coronavirus in the gastrointestinal tract in these children could be priming the immune system to overreact to adenovirus-41F by producing high amounts of inflammatory proteins that then damage the liver.

“We suggest that children with acute hepatitis be investigated for SARS-CoV-2 persistence in stool” and for other signals that the liver damage is happening because the spike protein of the coronavirus is a “superantigen” that over-sensitizes the immune system, the researchers said.

Other experts have put forward the theory that, as a result of social distancing and other COVID-19-related countermeasures, young children have had less of a chance to be exposed to adenoviruses, which would have helped build up their immunity.

In such cases, it is theorized the children’s immune systems may respond to an adenovirus infection by over-producing inflammatory proteins.

More study is required to confirm either theory, according to Dr. Rima Fawaz, a pediatric liver disease specialist from the Yale School of Medicine.

Tom Ozimek and Reuters contributed to this report.