• Scientists found a link between common childhood respiratory viruses and the mysterious 2022 hepatitis outbreak
• A study involving American children found that the kids who suffered from the unexplained disease had multiple "helper" viruses
• The study comes as the number of severe acute hepatitis in kids has slowly decreased

Scientists have linked common childhood respiratory viruses to the sudden and mysterious 2022 hepatitis outbreak in kids that puzzled health experts worldwide.

The study, which involved American children, provided further evidence that the hepatitis cases may have been caused by simultaneous infection with several common viruses. These include one that is known as adeno-associated virus type 2 or AAV2.

Common Viruses Linked to Hepatitis Outbreak

This particular virus is not typically associated with disease and requires a second "helper" virus to replicate. Experts found that many of the children who had unexplained hepatitis, or inflammation of the liver, were infected with multiple helper viruses.

While the idea remains speculative for now, the timing of the hepatitis outbreak could be related to the loosening of COVID-19 pandemic precautions. As per the New York Times, this left large numbers of young kids exposed to common viruses that they had not yet encountered.

In a statement, the author of the new study, infectious disease specialist and microbiologist at the University of California, Dr. Charles Chiu, said that the situation may have been a result of a population that was highly vulnerable to being infected with several viral infections.

The team's research was published in Nature on Thursday alongside two British studies that also implicated AAV2 in various hepatitis cases. Last summer, preliminary versions of the two separate studies were posted online.

The consistent findings of the three studies were "quite striking," said the head of the gastroenterology and hepatology department at the Charite University Medical Center in Berlin, Dr. Frank Tacke, who was not involved in any of the research. However, he did write an accompanying commentary where he noted that the fact that three independent groups found similar results from different areas worldwide makes the conclusion convincing.

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A Declining Number of Severe Acute Hepatitis

Tacke argued that many children were suddenly exposed to various viruses following lockdowns or had poorly trained immune systems. According to CNN, these factors could have increased susceptibility to otherwise harmless viruses.

The American study analyzed tissue samples of young kids in the U.S. and detected AAV2 in 93% of 14 cases but only 4% of 113 controls. The team discovered that all of the children infected with the virus had co-infection with a helper virus that was determined to be either human herpesvirus six or Epstein-Barr virus, which would promote AAV2 replication.

The authors of the study wrote that the results of their research suggest that co-infection with AAV2 could potentially result in more severe liver disease compared to infection by adenovirus or herpesvirus alone.

The findings come as AAVs are not considered pathogenic on their own, which means that more research is needed to establish a direct causal link with severe acute hepatitis. Health experts recommend frequent handwashing and staying home when sick to protect children despite declining cases of severe acute hepatitis in kids, said Earth.

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