1. What is hepatitis?
Hepatitis is an inflammation of the liver that can be caused by viral infections (including Hep-A, Hep-B and Hep-C viruses), alcohol consumption, toxins, medications and certain medical abnormalities.
Symptoms are nausea, vomiting, abdominal pain, dark urine, jaundice, fever and fatigue.
Acute hepatitis rarely occurs in children and the exact cause is often difficult to identify. Dr. Theresa Tam, Canada’s Chief Public Health Officer, also recalled this week that, even before the pandemic, about half of cases of severe pediatric hepatitis had no known cause.
In Canada, we see cases of indeterminate hepatitis every year, maybe two or three, normallysays Dr. Fernando Alvarez, director of the liver transplant program at CHU Saint Justine.
2. How many cases have been reported?
According to a report released this week by the European Center for Disease Prevention and Control (New window)there are currently approximately 450 cases worldwide and 11 deaths (5 in Indonesia, 1 in Palestine and 5 in the United States).
In the UK, there are more than 160 children under the age of 16 affected. Eleven of them received a liver transplant. In the United States, where 109 cases have been identified, 90% of children have been hospitalized; fifteen of them needed a liver transplant.
Cases have also been reported in Italy (36), Portugal (22), Argentina (8), Brazil (8), Costa Rica (2), Indonesia (15), Israel (12), Japan ( 7), Panama (1), Palestine (1), Serbia (1), Singapore (1) and South Korea (1).
In Canada, as of May 13, there are 7 cases in Ontario, 2 in Alberta and 2 in Manitoba.
It remains to be determined whether this number represents an increase in cases of unknown origin compared to previous years.writes in an email a spokeswoman for the SickKids hospital in Toronto.
Cases are still relatively rare, but there are enough serious cases to monitor the situation closelysays Dr. Christopher Labos, Montreal epidemiologist.
The first cases were seen in Alabama, USA in October 2021, but researchers initially believed it was a localized problem. It was not until early April that the UK informed theOMSan abnormally high number of cases.
Dr. Labos specifies that it is still difficult to know with certainty the real number of cases of severe hepatitis in the world.
Now that the international community has been alerted, we will be able to better detect the cases, we will be able to make associations between them and thus better understand the cause.
3. What hypotheses are studied to determine the cause?
Drs. Labos and Alvarez say the researchers aren’t ruling anything out.
For now, environmental factors do not seem to be involved. The viruses normally associated with viral hepatitis (Hep-A, Hep-B and Hep-C) were not detected in these children.
Another element is clear, according to Dr. Labos: the vaccination against COVID-19 is not in question since the majority of cases are less than five years old and are not yet eligible for the vaccine against COVID-19. Over 65% of children with severe hepatitis in the UK and over 80% of children in Europe were unvaccinated.
Everything else is possible. It may be a combination of factors that caused the cases of hepatitissays Dr. Alvarez, adding that one should not jump to premature conclusions.
Dr. Labos suggests that it is possible that some of the recently reported cases are linked, while others are not.
The cause may not be found for some of these cases.
At the moment, authorities and researchers are mainly looking at two possible causes: an adenovirus and SARS-CoV-2.
4. Could an adenovirus be the cause?
According to Dr. Caroline Quach, microbiologist-infectiologist and pediatrician at CHUSainte-Justine, the adenovirus theory seems the most plausible. This theory is also the one that currently prevails in the United Kingdom.
Adenoviruses are viruses that spread through close personal contact. There are more than 50 types that can cause infections in humans (respiratory diseases, gastroenteritis, conjunctivitis, cystitis and, less frequently, neurological diseases).
According to the latest report from theOMS (New window)among 169 cases, 74 children tested positive for adenovirus, including 18 for adenovirus 41. In children, it usually causes acute gastroenteritis which presents as diarrhea, vomiting and fever.
In the UK, 72% of children tested positive for adenovirus. In Alabama, 7 out of 9 children had been infected with an adenovirus.
But according to theOMS
although adenovirus is currently thought to be an underlying cause, it does not fully explain the severity of the cases. For example, no child in Israel with severe hepatitis tested positive for adenovirus.
« This adenovirus has been detected in some cases, but not in all. It may be a plausible theory, but it doesn’t explain everything. »
Also, according to Dr. Alvarez, adenovirus type 41 is not generally known to cause hepatitis in healthy children.
In those who are not on medication or who are not immunosuppressed, hepatitis caused by adenoviruses is usually mild or almost non-existent.
Dr. Quach, like other experts, wonders if the adenovirus possibly involved has a different genotype, which would lead to more serious lesions than what is usually observed.
The researchers also wonder if the fact that children were less exposed to adenoviruses during the pandemic could partly explain this increase in hepatitis. Sudden and more frequent exposure to adenoviruses when sanitary measures were lifted may have resulted in a more vigorous immune response in some, causing severe hepatitis.
5. What about SARS-CoV-2?
Researchers are also investigating the potential role of SARS-CoV-2.
Another theory would be COVID-19, which wouldn’t be surprising given the recent number of cases, particularly in the UK and the US, where many cases of hepatitis have been reported. But not all children with hepatitis tested positive for COVID-19says Dr. Labs.
According to Dr. Alvarez, it is known that a COVID-19 infection can increase the incidence of hepatitis in some people, but that, generally, these hepatitis are not as serious as those currently studied.
In Israel, 11 out of 12 children had COVID-19. However, of the eight cases recorded in Alabama, none had been diagnosed with COVID-19 when admitted to hospital. It is not known, however, whether these children have been infected in the past and it is not known how many of the other children with hepatitis in the United States have been infected with COVID-19.
In the UK, only 18% of children tested positive for SARS-CoV-2 while in hospital. In Scotland, 8 out of 13 children tested negative in the PCR test.
and Europe, (New window) only 12% of the 173 cases were diagnosed with COVID-19 through a PCR test. On the other hand, among the 19 cases where a serological test was done (to detect a previous infection), 74% were positive for COVID-19. This is why several researchers believe that a serological test should be carried out in all children with severe hepatitis in order to know exactly how many of them have been infected with SARS-CoV-2 in the last few months.
Furthermore, researchers in India (New window) estimate that COVID-19 may have caused dozens of unexplained cases of severe hepatitis between April and July 2021.
Their non-peer-reviewed study shows that among 475 children with COVID-19, 47 had severe hepatitis. Among these 47 children; 37 were classified as having what the researchers called
hepatitis associated with COVID-19 .
The only common factor we found was that they were all infected with COVID-19 or they all had a previous infection of COVID-19told CBC (New window) Dr. Sumit Rawat, lead author, microbiologist and associate professor at Bundelkhand Medical College, Madhya Pradesh, India.
He adds that hepatitis cases suddenly decreased when COVID-19 infection rates dropped, but increased when the number of cases was high. According to Dr. Rawat, this is another sign that COVID-19 could be involved.
Another hypothesis, put forward by researchers in The Lancet (New window)is that a co-infection of an adenovirus and SARS-CoV-2 would have possibly caused these hepatitises.
6. Should parents be worried?
The three doctors say that the authorities must be on the alert, but not to panic. The number of cases remains relatively low, they recall.
For most children, gastro is a common illness. But as usual, it is necessary to consult if it lasts more than a few days and if there are signs of yellowing in the eyessays Dr. Alvarez.
Dr. Quach would like to remind you that the adenovirus can be easily destroyed with common cleaning products.
We must continue to maintain our usual hygiene practices.
For his part, Dr. Labos adds that it is wise to continue to protect children from COVID-19 by wearing the mask in crowded and closed places.
It’s common sense, even if we discover that SARS-CoV-2 is not the cause of hepatitis.