Over the past seven months, 180 previously healthy children in the United States have had unexplained hepatitis, yet public health investigators are no closer to answering two fundamental questions: What’s the cause of the mysterious illness, and is it actually driving a spike in such cases?
In an average year, up to 2,000 children are hospitalized with hepatitis, Dr. Jay Butler, the Centers for Disease Control and Prevention’s deputy director for infectious diseases, said during a media briefing Friday. In up to half of those cases, he said, a cause is never identified.
“All we can say for sure at this point in time is we’re not seeing a dramatic increase in the number of cases” typically expected, Butler said.
The CDC reported Wednesday what appeared to be a startling jump in suspected cases: 180 unexplained and potentially severe pediatric hepatitis cases in 36 states, up from 109 reported May 6.
Most of the new cases, Butler said Friday, were the result of a retrospective analysis. That is, doctors looked back on their patients over the past seven months to find previously unidentified cases.
A handful, he said, were new cases that occurred in the past two weeks.
The vast majority of patients recovered, but some had severe complications. Fifteen of the 180 children required a liver transplant. The CDC is also investigating six deaths.
Testing in recent cases has revealed that about half had evidence of an adenovirus, specifically adenovirus type 41. But there is no proof yet that the virus — which usually causes mild upset stomach — is behind the liver inflammation.
The number of new unexplained pediatric hepatitis cases has swelled to more than 600 worldwide, the European Centre for Disease Prevention and Control said this week.
Will Irving, a professor of virology at the University of Nottingham in the United Kingdom, suggested that a relaxation of mitigation measures as the COVID-19 pandemic winds down may be behind the apparent uptick.
That is, if there’s an infectious agent that causes hepatitis that would normally be seen in any given year, it could have been suppressed during lockdown and increased focus on hygiene.
“As that’s relaxed, we’re starting to see a resurgence,” Irving said Thursday during a media briefing hosted by the nonprofit Science Media Centre. “It’s the nature of infectious diseases that they will come back and amplify, and you get a small spike.”
While alarming, these cases are rare. Symptoms may include nausea and vomiting, as well as profound fatigue and loss of appetite.
The most glaring symptom has been jaundice, or a yellowing of the skin and eyes.
Other symptoms can include fever, stomach pain, dark urine and light-colored stool.
This story first appeared on NBCNews.com.