Do cold viruses cause severe hepatitis in children? What you need to know about adenoviruses

Virologist Celso Cunha admits “skepticism” about the possibility of an adenovirus causing severe hepatitis of unknown origin, which has already affected nearly 200 children worldwide, caused one death, and forced 17 liver transplants. Pediatrician Manuel Ferreira de Magalhães points out that adenoviruses are common at this time of year and usually cause conjunctivitis or gastroenteritis, a mild and self-limiting illness.

The hypothesis was put forward by British experts: adenovirus may be the cause of acute hepatitis of unknown origin, which has already been diagnosed in nearly 200 children in several European countries and the United States.

According to data published during the Congress of Microbiology and Infectious Diseases in Lisbon, the latest data suggest that the adenovirus strain F41 is the most likely cause of hepatitis, which mainly affects children under 10 years of age. Other possibilities are being explored, namely whether pandemic and covid-19 restrictions have weakened the youngest’s immune system and left them more vulnerable to diseases that would not have serious consequences in other situations.

But adenovirus is not usually associated with hepatitis. “It’s a kind of virus with genetic material in one DNA molecule. There are several types of adenoviruses and they can infect different organs with very different pathologies,” explains Celso Cunha, a virologist at the Universidade Institute of Hygiene and Tropical Medicine. Nova de Lisboa .. “However, the most common diseases are respiratory diseases,” adds an expert who admits a somewhat strange possibility that adenovirus can cause this serious liver disease in children.

“I don’t know what the suspicions are based on, I don’t know if there was any genetic material in the virus or if there were antibodies that are different things and give different clues.”refers to. “In addition, adenoviruses are very common and are present in all animals, do not have major characteristics, or normally cause serious illness. They are viruses that circulate around and cause us to catch a cold from time to time.”points Celso Cunha. “The fact that they cause this type of hepatitis in children is a novelty, because adenovirus doesn’t usually cause this kind of liver disease. But there’s a lot of speculation.”the virologist says.

The most unusual case of acute hepatitis in Celso Cunha in recent weeks is the number of transplants that have already been performed – a total of 17 liver transplants, or about 10% of the cases detected. complete and irreversible liver damage. “It is a complete failure of the liver, which sometimes occurs in fulminant hepatitis, but these are relatively rare. Usually, a liver transplant is made in the case of hepatitis C or B, in the case of a chronic disease, and the liver begins to degenerate slowly. cirrhosis and then carcinoma, but it can take years, especially today, with better drugs to control hepatitis C and control hepatitis B, “the expert says.

According to laboratory tests, the results of which were published worldwide by health authorities, none of the hepatitis-related viruses (A to E) were detected in children diagnosed with this acute hepatitis of unknown origin.

Genetic modification of adenovirus?

The possibility that there is a genetic change in the adenovirus strain, for example, can be raised, admits Celso Cunha. But he warns: “These DNA viruses do not have a very high mutation rate than RNA viruses, such as coronaviruses, hepatitis C, HIV or influenza viruses, which collect mutations and have the ability to change genetic segments during cell replication,” he stresses.

“I see a little skepticism that it could be something like this. First, we need to find out concretely whether the culprit is really an adenovirus. possible.”emphasizes the virologist.

“There are dozens of adenoviruses, they are well-studied viruses, because with them we have made fundamental discoveries about the function of cells,” also emphasizes an expert from the Institute of Hygiene and Tropical Medicine. But are they really behind children with acute hepatitis? “Right now and based on what I’ve read in the papers, I’m not betting,” he admits.

In a report published in the meantime, the World Health Organization also acknowledges that adenovirus, one of the hypotheses, “does not fully explain the severity of the clinical picture,” although the F41 strain of adenovirus has been observed in many. of children with hepatitis – for example, about 75% of English children. “Although cases of hepatitis have been reported in immunosuppressed children with adenovirus infection, adenovirus type 41 is not a known cause of hepatitis in healthy children,” the WHO document states.

The WHO has also stressed that it has not found an association between cases of acute hepatitis in children and the consumption of covid-19 vaccine or any type of food or medication.

“The causes are still being thoroughly investigated. We are investigating several underlying factors, both contagious and non-contagious,” WHO expert Philippa Easterbrook said at a news conference in Geneva on Tuesday.

Conjunctivitis and “nasal pus”

Manuel Ferreira de Magalhães, a pediatric lung specialist, admits that in his clinical practice he has observed a large number of children with typical cases of adenovirus infection in recent months, but they are “in line with normal seasonality.” virus, assures. “Adenoviruses are viruses that we have in the community all year round and can naturally cause disease all year round. But they achieve a higher incidence in the winter and spring months, just when we are, and give different types of disease, respiratory or gastrointestinal,” says the pediatrician. .

The most common diseases caused by adenoviruses are colds, pharyngitis, or bronchitis, these in younger children. “Traditionally, adenovirus is associated with viral conjunctivitis and can cause gastroenteritis and diarrhea.”shows Manuel Ferreira de Magalhães.

As for the hypothesis put forward by British doctors that we have a more severe adenovirus strain and more severely affecting the gastrointestinal tract and liver, the pediatrician admits that “it is one of the hypotheses on the table” and adds that the acute hepatitis cases now recorded can also be explained by: over the last two years, the number of infections has generally decreased significantly as a result of the restrictive measures and restrictions imposed by the pandemic.

Ferreira de Magalhães recalls what happened last year, for example, when the cause of bronchitis and an unusual respiratory virus were more common in the cold months: “Because of the situations, we changed the dynamics and seasonality of the virus,” says the pediatrician.

The lower exposure of children to the disease over the past two years, which is also one of the hypotheses put forward by British experts about the severity of diagnosed liver inflammation, remains a factor to consider, says Manuel Ferreira de Magalhães

However, after reading technical reports of acute hepatitis cases in the United Kingdom, where most cases are reported, the pediatrician asks for caution when blaming adenoviruses: “Until now, we’ve always been under speculation.”

How to catch (and prevent) adenoviruses

Of the usual ways to infect adenoviruses, Manuel Ferreira de Magalhães points out that these, like covid-19, infect in droplets and contact cases, so measures to reduce infections during a pandemic can help keep the virus at bay. distance and respiratory hygiene. “But unless you suddenly realize that there was indeed a severe mutation in the adenovirus, I see no reason to go back into the masks,” says the expert, noting that this type of virus is usually self-limiting and disappears on its own. .

“Adenovirus can be more severe in immunocompromised children, but it happens with any infection. It can cause cystitis, hepatitis, nephritis, it can occur in many forms and progress in severity. But this, I stress, is very rare. Adenovirus occurs with fever associated with bleeding. nose and conjunctivitis. In babies, it can cause bronchitis, “says the pediatrician.

Good hygiene of the hands, surfaces, and food is a way to prevent the spread of the most common infections and also to prevent the spread of adenovirus, which may be the cause of this acute hepatitis.

Cases of acute hepatitis in children have already been reported in 12 countries, and at least 169 cases have been reported by the World Health Organization – according to the latest balance from 21 April. The United Kingdom has the highest number of cases, followed by Spain and Israel. Cases have also been reported in the United States, Denmark, Italy, France or Belgium. The WHO announced on Sunday that the child had died of the disease, without revealing in which country the death took place.

The European Center for Disease Prevention and Control has already announced that it will follow up on the reported cases and intends to publish a rapid risk assessment tomorrow, Thursday.

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