Adenovirus F41, the main 'suspect' of childhood hepatitis cases

Almost half of the 'mysterious' infections in minors have this pathogen in common and in 18 cases the F41 subtype has been identified. Infections "can occur through the air or water, through fecal-oral contamination"

The investigation continues into the cases of childhood hepatitis of unknown origin have already been detected in 12 countries. According to data from the World Health Organization, so far there have been confirmed 169 cases, all in the northern hemisphere.

The United Kingdom, the first country to raise the alarm on the 5th, has recorded 114 cases to date; Spain follows, with 13 (8 confirmed and 5 possible); Israel, with 12; United States, with 9; Denmark with 6; Ireland, which has reported less than 5; Holland, with 4; Italy, also with 4; Norway and France with 2 respectively and Romania and Belgium with two cases.

Although health authorities are still trying to find out the origins of these hepatitis that They have provoked a death and have required the liver transplant of 17 affected (10% of cases), there are still few certainties about the possible causes and mechanisms of the disease.

According to data presented this Monday at the Congress of the European Society of Clinical Microbiology and Infectious Diseases (ECCMID), which is being held these days in Lisbon (Portugal), one of the main suspects is adenovirus F41. Although, "for the moment all hypotheses remain open", as Aikaterini Mougkou, a researcher at the European Center for Disease Control (ECDC), pointed out at the meeting, this subtype of Adenovirus is postulated as one of the possible causes.

In 74 of the cases, a adenovirus infection and in 18 of them it has been possible to identify the subtype F41. According to Raúl Rivas, professor of Microbiology at the University of Salamanca, adenoviruses are very common pathogens in humans and can cause different types of infections in the respiratory tract, eyes, intestine, liver, urinary tract or adenoids.

WHAT ARE THE SYMPTOMS CAUSED BY THIS ADENOVIRUS?

Specifically, serotypes 40/41 of species F of adenoviruses are associated with cases of pediatric gastroenteritis. These conditions can be serious and require hospitalization, especially in children under two years of age.

"Some previous work had already pointed out other adenoviruses as a possible cause of liver failure in children"says Rivas, although it is a rare association that has mainly been reported in immunocompromised patients.

HOW IS THIS PATHOGEN TRANSMITTED AMONG CHILDREN?

These are microorganisms that are transmitted from one person to another very easily, through secretions or contaminated objects. "It can be through the air or through water, through fecal-oral contamination", he clarifies.

For Jesús Rodríguez-Baño, head of the Infectious Diseases service at the Virgen Macarena University Hospital in Seville and former president of ECCMID, right now "the adenovirus hypothesis is the most plausible", although the specialist suggests that it could be a new variant with a more hepatotropic profile, that is, with a greater capacity to produce liver damage.

There are many questions that still need to be resolved, the specialist emphasizes. "We also don't know if all the cases are serious or what we are seeing is the tip of the iceberg that hides many other milder cases underneath," he points out.

MORE CIRCULATION OF ADENOVIRUS

At the aforementioned congress, Meera Chand, director of clinical and emerging infections at the United Kingdom Health Security Agency, pointed out that the country has also observed a significant increase in adenovirus circulation in the last few weeks. The increase contrasts with the low transmission previously detected, during the peak months of the pandemic.

In that sense, although The involvement of other toxic or environmental factors is not ruled out., it is being investigated that the hepatitis are related to increased susceptibility to exposure to Adenovirus. Authorities, he clarified, are also working to identify whether new variants of adenovirus or other pathogens of interest are circulating, as well as whether previous infection by COVID-2 or other viruses can lead to greater vulnerability.

In 19 of the patients, it was detected coinfection with adenovirus and SARS-CoV-2. The health authorities They completely rule out any relationship with the Covid-19 vaccine since the vast majority of those affected had not been vaccinated.

SPAIN, WHAT IS THE PROFILE OF DETECTED CHILDREN LIKE?

At the moment, the cases have been diagnosed in children between one month and 16 years old, although most of those affected were under 5 years.

According to data from the Ministry of Health, the ages of the cases registered in Spain (confirmed and probable) range between 18 months (one case) and 16 years. Only one of those affected, the little one who needed to undergo a transplant, has tested positive for Adenovirus.

One of the Spanish minors affected has a history of recent travel to the United Kingdom and another had previously undergone chemotherapy treatment due to acute lymphoblastic leukemia.

Patients present a acute hepatitis, with a high level of transaminases (more than 500 IU/L). Many of the children suffer jaundice and gastrointestinal symptomsas the  abdominal pain, vomiting and diarrhea. The analyzes carried out rule out that the condition is due to hepatitis A, B, C, D or E viruses, which commonly cause hepatitis in children.

In the event of a suspicious case, Rodríguez Baño emphasizes, it is important that in addition to a thorough evaluation, taking into account their medical history and possible exposure to toxins, the samples obtained are sent and evaluated to reference laboratories that have the necessary molecular techniques to detect better the possible causes of the disease.