The World Health Organization (WHO) said that the number of children with hepatitis of unknown origin, which emerged in the United Kingdom and was later detected in many countries, has increased to at least 230 in the world. Three children in Indonesia have died from the mysterious liver disease, the country's health ministry said, raising the global death toll to at least four and leaving doctors from the United States to Asia scrambling to find answers.

This severe strain of acute hepatitis has been identified in nearly 230 children in 20 countries, the World Health Organization said, raising concerns of the disease's "unknown origin."

The symptoms afflicting the children include nausea, vomiting, diarrhea and abdominal pain – before their livers showed signs of inflammation. At least one death was previously reported.

Indonesia's Health Ministry said that three children had died in hospitals in the capital Jakarta last month, after displaying some of these symptoms.

The children – aged 2, 8 and 11 – also had fever, jaundice, convulsions and loss of consciousness, the ministry's spokesperson Siti Nadia Tarmizi told Agence France-Presse (AFP).

"At the moment, we suspect the cases as acute hepatitis, but we need to confirm that they are not due to known hepatitis viruses A, B, C, D and Rb," Tarmizi said.

She added that the Health Ministry was currently investigating the cause of the disease by running a full panel of virus tests.

The ministry also called on parents to immediately take their children to hospital if they showed any sign of the symptoms.

This emergence of a possible new disease afflicting only young children – most are under the age of 10 with no underlying conditions – has sent ripples of concern through a global health community already grappling with COVID-19.

According to the WHO, the majority of the cases have appeared in Europe, particularly in Britain when there was an "unexpected significant increase" in cases among young, previously healthy children.

In the United States, the Centers for Disease Control and Prevention published a study Friday on a cluster in Alabama, where nine children had also tested positive for a common pathogen called adenovirus 41.

The pathogen is known to cause gastroenteritis in children.

But "it is not usually known as a cause of hepatitis in otherwise healthy children," the agency had said.

Adenoviruses are commonly spread by close personal contact, respiratory droplets and surfaces. There are more than 50 types of adenoviruses, which most commonly cause the cold, but also many other diseases.