by Roberta Jansen
A mysterious type of acute hepatitis has attracted the attention of health authorities in different countries of the world over the last few weeks. The disease, which affects children and is already investigated even in Brazil, is not caused by any of the known hepatitis viruses (A, B, C, D and E) and may have among its causes an as yet unclear relationship between covid -19 and a type of adenovirus. The World Health Organization (WHO) has registered 348 cases of the disease until this week. Most children had gastrointestinal symptoms, jaundice and, in some cases, acute liver failure and a condition that eventually led to death.
The Ministry of Health created a situation room to monitor 41 suspected events of acute hepatitis of unknown origin registered so far in the country. Among them is that of a 14-year-old girl from Ibimirim, Pernambuco, who was hospitalized in a coma and had to undergo an emergency liver transplant on Friday. With this, there are six suspected cases of the disease in Pernambuco alone.
The first hypothesis was raised by UK health authorities. There, the first cases were recorded and it was hepatitis caused by an adenovirus. Studies have shown that up to 70% of patients have tested positive for adenovirus 41F. It affects more children, young people and immunosuppressed people. It causes a cold or intestinal problems.
“Initially, it was thought that the adenovirus would be the cause of acute hepatitis, but the fact is that it did not appear in all cases”, explained infectious disease specialist Marcelo Simão, from the Federal University of Uberlândia, in Minas Gerais. “In many children who presented severe conditions, it was not possible to isolate the virus; and in some in which a transplant was performed, the virus was not found in the removed liver.”
Experts also noted that many children had had Covid-19 prior to acute hepatitis. A study published in the Lancet last week then proposed a new hypothesis. According to the work, a combination of the two infections would be causing acute liver disease. Remaining particles of Sars-CoV-2 in the intestinal tract of children would be serving as a trigger for an exaggerated reaction in the immune system to a later infection by adenovirus 41F. The coronavirus spike protein is considered a superantigen. It makes the immune system more sensitive. Thus, it would potentiate the effect of adenovirus 41F. Typically, this virus does not cause more serious problems.
The reaction would be similar to that caused in Multisystem Inflammatory Syndrome. This condition has been identified in children with long-term covid. In these cases, there is an abnormal activation of the immune system because of the superantigen. It triggers an extremely inflammatory autoimmune reaction. Any subsequent exposure to an adenovirus could provoke an even stronger reaction from the body. This is what may be happening in cases of acute hepatitis.
“The most accepted hypothesis today is that this hepatitis is being caused by an exaggerated immunological reaction caused by the combination of these two viruses that ends up attacking the liver”, said Simão, whose name integrates the list of the Stanford University, in the USA, of the most influential scientists in the world. “Why the liver? We don’t know yet.”
Another question that has not yet been clarified, according to Simão, is why cases of acute hepatitis only started to be noticed now, two years after the beginning of the pandemic. A possible explanation would be related to the Sars-CoV-2 variant currently in circulation.
For the president of the Society of Infectious Diseases of the Federal District, José David Urbaez Brito, the hypothesis of the combination of the two viruses is currently the most likely to explain cases of acute hepatitis in children, although it is not yet closed.
“What is different at this current moment in our lives is that we are suffering the continuous modulation of a pandemic”, said Brito. “We are bombarded minute by minute by an infectious agent circulating at a gigantic magnitude; anything new that appears could have something to do with it.”
Data from the WHO and from studies carried out in Israel, the United States and India reinforce the hypothesis. The Israeli work, coordinated by Yael Mozer Glassberg of the Schneider Children’s Medical Center, showed that 11 of 12 children who had hepatitis had had Covid-19. None of them, however, tested positive for the adenovirus.
WHO Europe pointed out in a report released this month that up to 70% of children under the age of 16 who developed acute hepatitis were previously diagnosed with Covid-19. In addition, experts explained, other children may have had the disease mildly or even asymptomatically; that is, without an official diagnosis.
A study carried out in the United States and published in the Journal of Pediatric Gastroenterology and Nutrition analyzed the case of a 3-year-old girl. The girl developed liver failure a few days after recovering from a mild covid.
“The findings from the patient’s liver biopsy and blood tests are consistent with a type of autoimmune hepatitis that may have been triggered by Covid,” explained pediatrician Anna Peters, a gastroenterologist at the Cincinnati Children’s Hospital Medical Center in the US. , responsible for the study, when commenting on the work.
According to the expert, it is impossible to prove the existence of a direct link between covid and liver disease. But the virus may have triggered an abnormal immune response. She would be the generator of the liver attack.
A survey carried out in India last year followed 475 children who had covid in the country. Of them, 47 had acute hepatitis. Recently, with new cases emerging in Europe and the US, researchers have turned to this 2021 Indian study.
“The only common factor we found among these children was that they had all been infected with Covid,” the study’s lead author, Sumit Rawat, an associate professor at the Bundelkhand School of Medicine in Madhya Pradesh, India, said in an interview with international agencies. “Proving that covid is in fact causing this hepatitis will still require a lot of study, but an important clue is that hepatitis cases fell when Sars-CoV-2 stopped circulating in the region and rose again when covid was high. .”
NOTHING WITH VACCINE
The link between cases of acute hepatitis and the vaccine against covid, however, has been completely ruled out. There is no direct relationship between vaccination and hepatitis. In addition, most children who presented acute hepatitis were under 5 years of age. That is, they had not been immunized against covid.
Experts believe that new emerging virus pandemics – and their eventual ramifications – are likely to become increasingly common, because of man’s impact on the environment and climate. “We are living in a complicated world, with many new diseases, many new viruses; bacteria that we didn’t care about are now causing serious illness,” said Simões. “Despite technological advances, the challenges are increasing.”
José David Urbaez Brito recalled that, not by chance, we live in the so-called Anthropocene period. It is the first time that a living being, in this case man, has altered its environment in such a profound and often irreversible way until it started to name a geological era. “Man has altered geological and ecological chains, has significantly increased global temperature, causing a profound impact on the dynamics of infectious agents, notably viruses, which are very simple forms,” said Brito. “Narratives have the power to rationalize what happens, leaving us alienated; but the truth is that we live in an apocalyptic moment of gigantic dimensions, and the current pandemic is a symptom of that.”