The new cases are in addition to 70 others previously reported, according to Dr. Philippa Easterbrook, a senior scientist in the WHO’s hepatitis department.
The U.K. currently leads in cases with around 163, and only six countries are reporting more than five cases. The U.S. recently announced it was investigating 109 probable cases of “unknown origin” on Friday, and the WHO’s numbers reflect that addition.
The cases reported are a mixture of new cases and historic ones, Easterbrook said.
Toronto’s SickKids Hospital reported seven probable cases of severe acute hepatitis on Tuesday, all of “unknown origin,” in children between one month and 16 years of age. The cases were identified between Oct. 1, 2021 and April 30, 2022, and SickKids said it remains to be seen whether the cases recently reported are a spike from previous years.
It is still unclear how many cases total there are across Canada.
Hepatitis is usually caused by one of several contagious hepatitis viruses, like A and B, which have not been found in the affected children in Toronto.
Chief public health officer Dr. Theresa Tam said Friday that the Public Health Agency of Canada (PHAC) has contacted its 17 pediatric centres across the country to try to get a better understanding of the situation. She noted that before the pandemic, about half of severe hepatitis cases among children had no known cause.
“We’re still at the investigation stage of trying to figure out whether any of these cases are indeed linked at all. There’s always been hepatitis and some severe cases of hepatitis in children pre-pandemic and one would expect post-pandemic as well,” she said.
PHAC said in a statement Tuesday that it does not know if Canada is seeing an increase in cases of acute hepatitis of unknown cause in children.
“More information is needed to assess the situation and any potential risks to people in Canada,” spokesperson Tammy Jarbeau said. “We are working closely with provincial, territorial, and international partners on this evolving event.”
While the cause of the global cases is still unknown, Easterbrook said a strong correlation has been found with adenovirus, a common ailment that typically features cold or flu-like symptoms. Over 70 per cent of the U.K.’s cases tested positive for adenovirus.
Easterbrook said adenovirus type 41 was most common among the cases, which typically causes diarrhea, vomiting and fever, as well as respiratory symptoms, according to the WHO. She said more data from the U.K. will hopefully come within the week to see whether the adenovirus is a correlation or causal.
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COVID-19 was also detected in 18 per cent of the U.K. cases and the WHO is investigating how many of the total hepatitis cases previously had the virus.
“An important consideration is the role of COVID, either as a co-infection or past infection,” Easterbrook said.
The WHO is currently working closely with all regions in its active investigation, and is co-ordinating with the U.K. Health Security Agency.
Hepatitis impacts the liver and can be detected by the onset of jaundice (yellow eyes), dark urine and/or pale stool. Five children have died so far in the U.S. and there have been at least three deaths in Indonesia from the illness.
— with files from Gabby Rodrigues and The Canadian Press
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