Study links common childhood virus to rare cases of hepatitis

Last year, serious incidents were reported, hepatitis of unknown cause Among previously healthy children, health experts around the world were baffled.

now, small new study Evidence that it may have been caused by co-infection with multiple common viruses, including the virus known as adeno-associated virus type 2 or AAV2, is contained in the number of American children.

AAV2 is usually disease-free and requires a second ‘helper’ virus to replicate. Researchers found that many children with unexplained hepatitis or inflammation of the liver were infected with multiple helper viruses.

While this idea remains speculative, the timing of the outbreak may have been related to the relaxation of pandemic precautions, leaving many young children exposed to a common virus they had never encountered before. It is becoming

Dr. Charles Chiu, an infectious disease expert and microbiologist at the University of California, San Francisco, and author of the new study, said:

The study was published Thursday in the journal Nature. two British studies it was also related AAV2 in hepatitis cases.Preliminary version of British Studies posted online last summer.

Dr. Frank Takke, head of the Department of Gastroenterology and Hepatology at the Charité University Medical Center in Berlin, said the consistent findings were “very impressive,” although he was not involved in the study. “The fact that three independent groups have found this from different parts of the world actually makes it really compelling.”

Still, the findings are inconclusive, and many questions remain about how these infections can lead to hepatitis, whether AAV2 plays a causative role, or whether they are ‘just a bystander’. uncertainties remain. has become really common Whether it was part of last year or a previously unrecognized phenomenon.)

The incident Autumn 2021 But after peaking last spring and summer, it seems to have tapered off, experts say. By July last year, 1,000+ possible cases reported in 35 countries, Including US, according to the World Health Organization.about 5 percent of children liver transplant neededand 2 percent died.

In some early studies, scientists found that many affected children infected with adenovirus, especially adenovirus 41, usually cause gastrointestinal symptoms. Adenoviruses are not generally known to cause hepatitis in healthy children, but are common helper viruses for AAV2.

This new study was a collaboration of academic researchers, state health departments, centers for disease control and prevention, and other institutions. Researchers studied biological samples from 16 of her American children in her six states who had hepatitis of unknown origin. All had previously tested positive for adenovirus. They also studied samples from 113 control children, including healthy children, children with gastroenteritis, and children with hepatitis from known causes.

Blood samples were available from 14 children with hepatitis of unknown origin. The researchers found AAV2 in 13 of those children, or 93%, compared with 3.5% of control children, of her 30 children with hepatitis associated with known causes. , no AAV2-positive test results were obtained.

Most children with unexplained hepatitis also tested positive for at least one herpes virus. This means that many people were infected with at least 3 viruses. AAV2, adenovirus, herpes virus.

In another small UK study, scientists found AAV2 in the blood and liver of affected children. Many were also infected with adenovirus and herpes virus. In one study, 25 of her 27 affected children shared an immune-related genetic mutation that is relatively rare in the general population. This finding suggests that this variant may predispose some children to hepatitis when infected with AAV2 and one or more helper viruses.

“On rare occasions, it may turn out to be a sort of full-on stormy event in which there is a unique subset of susceptible children,” Dr. Chiu said.

Further research is needed to determine whether one or more of these viruses directly damage the liver, he said.

Another explanation is that in a small subset of children, infection with multiple viruses triggers an overly strong immune response that damages the liver.

Identifying the mechanism would have important therapeutic implications, Dr. Tacke added. Antiviral drugs may be the best treatment if the virus is damaging the liver. If the cause is an immune overreaction, suppressing the immune response with steroids may be a better option, he said.