Although the rate of diagnosis of cases of hepatitis of unknown origin in children has started to decline, scientists’ knowledge of these infections remains “mixed”in part because of the lack of standards for data collection around the world.
While cases of acute hepatitis of unknown origin are nothing new in children, the recent increase in diagnoses, with no apparent cause, has scientists perplexed.
Speaking on Thursday (June 23) at a press briefing at the International Liver Congress in London, Phillippa Easterbrook, technical officer at World Health Organization (WHO) headquarters, said cases “have always been identified at a low level”.
Nor is the severity seen in recent weeks exceptional, 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.
However, what remains singular is the volume of cases observed, in particular in the United Kingdom, which has around 260 of the approximately 900 recorded worldwide.
What is also remarkable is that very little is known about how the infections arose. While the downward trend observed in Europe and the United States among cases of hepatitis of unknown origin is a “positive development”the reasons for the upsurge and recent decline are still unknown, Ms 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 past 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 come from the WHO Europe region. The majority of cases, 75%, are seen in young children under the age of five. Of the cases in Europe for which follow-up information is available, around 30% required admission to intensive care and almost 20% required liver transplantation.
The search for comparable data
Researchers are trying to answer the question of whether this is truly a new phenomenon, Ms 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 probably a new phenomenon and that they have “reliable data on this subject”other countries have reported the opposite.
The lack of standardization of surveillance at the global level is at the origin of this mixed picture. Countries do not all report their data in the same way, for example with regard to age distribution, and they do not all test for adenovirus in the same way.
“Everyone investigates differently”said Ms Easterbrook, adding that “we really need to have good quality data collected in a standardized way”.
Part of the conundrum, says Easterbrook, is that complex and expensive genetic tests are more difficult to access in low- and middle-income countries, so several variables are taken into account inconsistently.
Andreas Hoefer, expert in microbiology and molecular surveillance at the European Center for Disease Prevention and Control (ECDC), said Wednesday June 22 during a WHO webinar that in Europe, the lack of samples in laboratories is also a problem.
It’s not because they “don’t want to share” but rather because “The ethical considerations required to collect additional sample volumes from children are very complicated, and approval from an ethics committee is required to do so. »
“There is a very urgent need to find a way to collect, share and store enough sample collections”said Mr. Hoefer.
Lessons for the future
Ms. Buti, from AEEF, said that ongoing surveys 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, it is“an opportunity to really try to better understand this phenomenon”.
“Pediatric hematologists are thrilled as they have been waiting for this moment to draw attention to a rare and unusual phenomenon”she added.