Gadgets News

Scientists may have found the culprit behind the mysterious outbreaks of hepatitis in children

Several groups of scientists believe they have uncovered the probable cause from mysterious splash severe hepatitis last year that hospitalized and killed children around the world. Three In studies published this week, the teams detail evidence that a common but usually non-pathogenic virus was strongly associated with these cases, likely facilitated by co-infection with other common viruses. Affected children could also be genetically unlucky.

Early last year, UK health officials first reported on a cluster of severe hepatitis with cases dating back to autumn 2021. Hepatitis is a general term for inflammation of the liver, often accompanied by symptoms such as fever, fatigue, and jaundice (yellowing of the skin and eyes); in severe cases, this can lead to direct liver failure or death. These children did not test positive for any known causes of hepatitis, including a group of unrelated viruses named after the disease.

Other places will announce soon similar clusters. By July 2022, according to World Health Organization, more than 1000 cases of this severe unexplained childhood hepatitis have been reported in 35 countries. Most of the children were hospitalized; about 5% became so ill that they needed a liver transplant; and 2% eventually died as a result.

There are various theories about the origin of these clusters. Many, but not all, children have tested positive for adenoviruses, common microbes that can cause disease; some have also recently had SARS-CoV-2, the cause of covid-19. But the harm caused by these viruses is not usually associated with the severe liver damage seen in these children, indicating that some other catalyst is at work. One theory debunked was that COVID-19 vaccines were to blame, but many of the victims the children were too young to get shots.

IN three documentation published This week in Nature, independent groups of scientists describe evidence pointing to a common suspect, though not working alone: ​​adeno-associated virus type 2 (AAV-2). Each group found that the vast majority of the cases they studied were newly infected with AAV-2, and at much higher rates than similar controls or patients who developed hepatitis for known causes. Some teams also found signs of AAV-2 infection in children’s livers and circumstantial evidence that the organ was damaged as a result.

AAB-2 strange, even among microbes. It is a satellite virus, meaning that it can only make more of itself inside a cell when another “helper” virus infects the same cell. As the name suggests, adenoviruses are a common helper virus for AAV-2, but herpesviruses can also be its partner. In many of these children, scientists also found these helper viruses, and sometimes even more than one.

AAV-2 isolated from affected children do not appear to be genetically different in any significant way from other known strains, but one study by British scientists offers another key factor behind the clusters: most of them had the same gene variant that is known to influence our immune response, and at a faster rate than in the general population. It is possible that carrying this variant made the children more vulnerable to the unlikely scenario that led to their hepatitis, the authors say.

“It may turn out that on rare occasions you have a sort of perfect storm of events where there is a subset of children who were uniquely susceptible,” Charles Chiu, an infectious disease specialist at the University of California, San Francisco and one of the authors of the study on children in the USA said New York Times.

These studies alone are not evidence that AAB-2 is to blame for the clusters. First, they are all based on a small sample of patients, and in only two of the many countries where cases have been reported (USA and USA).TO). Eat questions still remain unanswered about exactly how AAV-2 can do this with children,and we also don’t know why these clusters appeared exactly when they appeared.

It is possible that the relative absence of other common infections in the early years of the pandemic led to an immunological gap such that outbreaks of these diseases (and their rare complications) were temporarily larger than usual when people began to socialize regularly again. But data from the US indicated that the documented rate of unexplained hepatitis in children did not increase last year from pre-pandemic baseline levels. In other words, AAV-2 may have always been rare but permanent the cause of hepatitis, but we only now noticed it because we were finally looking for it. It is also possible that some countries did experience a surge last year and others did not.

Fortunately, the reported incidence of these unexplained hepatitis cases has dropped significantly since peaked last summer, so the immediate crisis seems to be over. But more research will be needed to confirm what these scientists found, as well as to better understand what exactly happened to these children and whether we can do something to prevent or reduce the risk of such events. cases in the future.

Source link

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button