When previously healthy young children began appearing in hospitals with defective livers last fall and this spring, surprised doctors and public health authorities did not know what was behind what they were seeing. Nor did they know if what they were seeing was new.
There have always been cases of hepatitis in children for whom no cause can be found; these cases are labeled pediatric hepatitis of unknown etiology. But these cases occur in very low numbers and are not well studied or traced. Thus, when doctors in Alabama and Scotland reported that they had seen more of these cases in a few weeks than normally in a year, they had no reliable statistics with which to compare the apparent increase.
Scientists at the Centers for Disease Control and Prevention have now made some estimates of the normal rate of the disease, at least in the United States. Her findings, published earlier this week in the online journal Morbidity and Mortality Weekly Report, may come as a surprise.
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His research suggests that there has been no increase in cases of pediatric hepatitis of unknown origin, at least in the United States. There has also been no increase in the number of pediatric liver transplants, which some of these children have needed. Similarly, the rate of detection of infections caused by adenovirus 41, a stomach error virus that has been implicated as a potential trigger for these cases of hepatitis, has not changed over time. inform the CDC scientists.
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(They note that UK authorities believe they may have seen a small increase in pediatric hepatitis cases, but the report they point out says the lack of pre-pandemic data there makes it difficult to be sure).
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The CDC’s findings do not identify what is causing cases of pediatric hepatitis of unknown origin, 290 of which are under investigation in that country. Elsewhere, some three dozen countries have detected cases since the UK sounded the alarm in early April. As of June 6, the World Health Organization had received more than 800 probable and suspicious cases.
But the CDC’s findings can help rule out some things. With rates unchanged since before the Covid-19 pandemic, a theory defended by Israeli scientists, which is a kind of post-Covid condition, is becoming more difficult to argue.
“It doesn’t mean that Covid can’t play a collateral role with all this yet. But I think this kind of data helps to support that this is probably not the cause,” said veteran epidemiologist Michael Osterholm. participate in the work of the CDC.
CDC researchers extracted data from four different sources that analyzed emergency department visits and hospitalizations for hepatitis of unknown etiology in children under 11, from January 2018 to March 2022 for the first time. and January 2019 and March 2022 for the second.
They also compared monthly liver transplant figures for children under 18 for whom the diagnosis was liver necrosis (liver failure) of unknown etiology from October 2017 to March 2022. Finally, they studied data from laboratory on stool samples tested by adenovirus 40 or 41. during the period October 2017 to March 2022 from Labcorp, a large network of commercial laboratories.
There were no statistically significant increases in hepatitis hospitalizations of unknown origin in the period following the onset of the Covid-19 pandemic; There was also no statistically significant increase in the number of liver transplants per month, the researchers found. The number of positive tests for adenovirus feces varied, within a range, before the pandemic and so did the post-pandemic. But the positivity rate last October, when the Alabama cases were detected until March, when Scotland began reporting cases, did not exceed pre-pandemic rates.
“The cases we are currently describing, at least the trends, do not appear to be different from those we described before the pandemic,” lead author Jacqueline Tate, leader of the gastroenterology team’s epidemiology team, told STAT viral CDC. an interview.
“I think that does indicate that with all the changes we’ve had with the pandemic … that doesn’t seem to have had the same impact on hepatitis trends, if it was a driving force.”
The work was done to set benchmarks, he said.
“We are trying to look at the landscape. Is there anything that has changed radically? We don’t believe it. But I think by looking at this and just realizing that we’ve improved the diagnosis, the accessibility of the improved information, maybe we can better explain what’s going on with this hepatitis, “Tate said.
The fact that reference rates have not changed does not mean that nothing is happening with pediatric hepatitis of unknown etiology, said Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. Rather, a couple of case groups, in Alabama and Scotland, may be giving the scientific community a chance to find out who has been responsible for some of the cases over time.
In the work of disease detectives, having reference data is crucial to differentiating something new from something recently recognized, said Jeffrey Duchin, a Seattle and King County Public Health Department health officer and a professor of infectious diseases. at the University of Washington.
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The apparent increase in cases could be an “improved detection”: higher detection, he said, adding that the CDC’s analysis is reassuring, suggesting that we are not seeing a significant increase in pediatric hepatitis. .
When medical events happen at very low levels (one unexplained case here, another there), it can be very difficult to get to the bottom of what is happening, said Osterholm, who has been involved in deciphering various public health mysteries.
But sooner or later, by chance, there will be a bunch of cases. And if the cluster is detected and the doctors involved work on it thoroughly and report its findings, as both groups did, other doctors will start looking and realizing that they also saw cases that fit that definition, he said. to say.
“It is not uncommon to see new conditions in which someone receives a series of five or six cases, someone else will look closely and get a series of five or six cases and soon these five and six, five and six will reach 700. “Osterholm said.
“With really complete information, like the CDC just presented here … the bottom line is that this could have been going on for a while before Covid came out at that low level,” he said.
Current care for pediatric hepatitis may help remove some of these cases from the “unknown etiology” column. But more and more different types of studies will be needed to identify what is causing them. Tate said the CDC currently has an ongoing study. So does the UK Health Security Agency, which has repeatedly said that adenovirus infection, possibly in combination with some other factor, appears to be related to these cases.