Hepatitis is inflammation of the liver, in reaction to viruses, toxins (drugs, poisons, etc.), autoimmune or genetic diseases. Often benign, its main symptoms – fevers, diarrhea, abdominal pain, jaundice – generally resolve quickly. More rarely, they can lead to kidney failure.
The United States is far from being the only country affected by this phenomenon of inexplicable hepatitis: dozens of cases have been identified across Europe, raising fears of a new epidemic. First reported in Scotland in late March, the number of registered cases worldwide is currently 191 (111 in the UK, 55 in 12 other European countries, 12 in the US, 12 in Israel and 1 in Japan), according to the European Center for Disease Control and Prevention (ECDC). The affected children ranged in age from one month to 16 years, but most were under the age of 10 and many under the age of 5. None had comorbidities.
Rather common viruses, adenoviruses are generally known to cause respiratory symptoms, conjunctivitis, or even digestive upset. Transmission occurs via the fecal-oral or respiratory route, with epidemic peaks often in winter and spring, and more often in communities (nurseries, schools, etc.). Most humans are infected before age 5. But their role in the development of the mysterious hepatitis is unclear.
“Right now we think an adenovirus could be the cause of these cases, but other environmental factors are still being studied,” said the Centers for Disease Control and Prevention (CDC), the US’s leading federal public health agency. . More specifically, the CDC points to the so-called “type 41” adenovirus, hitherto best known for causing severe gastroenteritis. While these adenoviruses are well identified as causes of hepatitis, so far they have only been in immunocompromised children.
After more than two years of pandemic and barrier gestures, the question of an immune “debt” that would make some children more fragile is also raised by some scientists, without certainty.
The European disease agency classified these unexplained cases of acute hepatitis this Thursday as a “public health concern”, while acknowledging that it is unable to accurately assess the risk. “Considering the unknown etiology (the cause of the disease, ed), the affected pediatric population and the potentially serious impact, this constitutes a worrying event for public health at this stage”, alarms the ECDC, in its first estimate of the public risk since the onset of the disease.
“The disease is quite rare and evidence of human-to-human transmission remains unclear. The cases in the European Union are sporadic with an unclear trend ”. The risk to children in Europe “cannot be accurately estimated,” the agency also notes. “However, considering the reported cases of acute liver failure, with cases requiring transplantation, the potential impact for the pediatric population is considered to be high.”
The main “working hypothesis” is, here too, that the disease is linked to adenoviruses. “An adenovirus infection, which would be mild under normal circumstances, would trigger a more severe infection or immune-mediated liver injury,” according to this lead. Other causes, particularly toxic ones, “are still under investigation and have not been ruled out but are considered less plausible,” the ECDC emphasizes.
While most of the cases were detected in late March, it was on April 15 that the World Health Organization (WHO) launched the alert and urged the countries concerned to launch a thorough investigation in order to ” determine the etiology of these cases and guide clinical and public health actions. ”Pending the results of this work, WHO recalls that washing hands regularly and wearing a mask can prevent adenovirus contamination and other common infections.