Although the frequency of diagnosing cases of hepatitis of unknown origin in children has begun to decline, researchers’ knowledge of these infections is still “mixed”partly due to the lack of data collection standards around the world.
While cases of acute hepatitis of unknown origin are nothing new in children, the recent rise in diagnoses, for no apparent reason, has confused researchers.
In a speech on Thursday (June 23) at a press briefing at the International Liver Congress in London, Phillippa Easterbrook, Technical Officer at the World Health Organization (WHO) headquarters, said cases “has always been identified at a low level”.
Nor has the severity seen in recent weeks been unusual, added Maria Buti, head of policy and public health at the European Association for the Study of the Liver (AEEF). “We had cases of acute hepatitis that even required a liver transplant a few years ago, and every year in our clinic we see this type of patient.”she said.
But what remains unique is the amount of cases observed, particularly in the United Kingdom, which has around 260 of the around 900 registered worldwide.
The remarkable thing is also that very little is known about how the infections originated. While the downward trend observed in Europe and the United States among cases of hepatitis of unknown origin is one “positive development”The reasons for the rise and recent fall are still unknown, Easterbrook said.
The main hypotheses so far are adenovirus and Covid-19, either independently or as cofactors of hepatitis.
Adenovirus was found in half of the samples in Europe, while active Covid-19 infection was detected in 10% of cases in Europe and the United States. Ms Easterbrook stressed that information about previous infections is important, but gathering information about the presence of antibodies is difficult.
More than 30 countries have reported cases of acute hepatitis of unknown origin, and about half of the countries have up to five cases.
Overall, half of the cases worldwide are from the WHO Europe region. The majority of cases, 75%, are seen in young children under five years of age. Of the cases in Europe for which follow-up information is available, about 30% required intensive care and almost 20% required liver transplantation.
The search for comparable data
Researchers are trying to answer the question of whether this is really a new phenomenon, Easterbrook said. “I have the impression that we have a somewhat mixed situation”she continued.
While some researchers in Europe and the United States have concluded that this is likely a new phenomenon and that they have “reliable data on this topic”other countries have reported the opposite.
The lack of standardization of surveillance globally is the reason for this mixed picture. Countries do not report all their data in the same way, for example in terms of age distribution, and they do not test everyone for adenovirus in the same way.
“Everyone investigates differently”said Mrs. Easterbrook, adding it “We really need to have good quality data collected in a standardized way”.
Part of the riddle, Easterbrook says, is that complex and expensive genetic tests are harder to access in low- and middle-income countries, so multiple variables are inconsistently considered.
Andreas Hoefer, an expert in microbiology and molecular surveillance at the European Center for Disease Prevention and Control (ECDC), said on Wednesday 22 June during a WHO webinar that the lack of samples in laboratories is also a problem in Europe.
It’s not because they “will not share” but rather because “The ethical considerations required to collect additional samples from children are very complex and ethical committee approval is required to do so.”
“There is an urgent need to find a way to collect, share and store enough sample collections”said Mr. Hoefer.
Lessons for the future
Ms. Buti, from the AEEF, said ongoing studies could pave the way for a better understanding of acute hepatitis in children. “This will help with future diagnoses in children as it is an in-depth data study”she said.
According to Mrs Easterbrook, that is it“an opportunity to really try to understand this phenomenon better”.
“Pediatric hematologists are excited as they have been waiting for this moment to draw attention to a rare and unusual phenomenon”she added.