Lhe UK alone has reported 160 cases, while only six countries have more than five sufferers.
“Significant progress has been made with respect to further investigations and the refinement of working hypotheses,” Philippa Easterbrook, of WHO’s Global Hepatitis Program, said at a press conference on Tuesday evening. .
Britain has coordinated a set of studies looking at affected children’s genes, immune response, viruses and other epidemiological studies, she said.
The United Kingdom had initially reported to the WHO on April 5 ten cases of severe hepatitis in Scotland, in children under ten years old.
In the United States, health authorities said Friday they were investigating 109 similar cases, including five fatalities. Three children also died in Indonesia.
“At this time, the main hypotheses remain those involving the adenovirus, also taking into important consideration the role of Covid, either as a co-infection or as a prior infection,” said Mrs Easterbrook.
Tests carried out last week confirmed that around 70% of cases were positive for adenovirus, with subtype 41 – normally associated with gastroenteritis – being the most common, she added.
Adenoviruses are usually spread through personal contact, respiratory droplets and surfaces. They are known to cause respiratory symptoms, conjunctivitis or digestive disorders.
The tests also showed that around 18% of the patients were positive for Covid-19.
“Next week we will focus on serological testing for previous Covid exposures and infections,” Ms Easterbrook said.
After the discovery of the first 169 cases, the WHO indicated that the hepatitis A, B, C, D and E viruses had not been detected in any of the patients.
Most patients presented with gastrointestinal symptoms, including abdominal pain, diarrhea and vomiting, or jaundice. Some cases have caused liver failure and required transplantation.
