A spreading hepatitis outbreak that killed six children has infectious disease experts scrambling to find answers.
The Centers for Disease Control and Prevention confirmed the sixth death last week. The CDC said the outbreak of the liver disease has expanded to 180 reported youth patients across 36 states and territories over the past seven months.
The number of cases increased by 71 in two weeks, but the CDC said most of those were "retrospective" patients who may have been ill weeks or months earlier.
"Not all are recent, and some may ultimately wind up not being linked to this current investigation," the CDC said in a statement. The agency said testing ruled out some of the viruses that commonly cause hepatitis.
Jay Butler, CDC deputy director for infectious diseases, said at a briefing that no common exposures or other patterns had been discovered. Lab tests are conducted to look more closely at the virus genome and other potential pathogens, such as SARS-CoV-2 – the coronavirus that causes COVID-19.
The CDC looked closely for any connection between the hepatitis outbreak and the virus that has killed 1 million Americans.
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Melissa Nolan, an assistant professor of epidemiology and biostatistics at the University of South Carolina Arnold School of Public Health, told USA TODAY the outbreak is almost certainly not related to COVID-19 vaccines.
"The fact is that a large number of cases involve kids less than 5 (years old) who were not eligible for the vaccine," Nolan said. "It's not a bad batch."
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Adenovirus was detected in nearly half of the children, a "strong lead," the CDC said.
Nolan noted that adenoviruses are generally linked to much less dangerous illnesses, such as pinkeye.
"It's not common to see severe liver damage from an adenovirus," she said. "This could be a new form of adenovirus. Or it could be something completely new."
Severe hepatitis in children remains rare, the CDC stressed.
"However, we encourage parents and caregivers to be aware of the symptoms of hepatitis – particularly jaundice, which is a yellowing of the skin or eyes – and to contact their child’s health care provider with any concern," the CDC said.
This article originally appeared on USA TODAY: 6th child dies from hepatitis outbreak in 36 states; CDC seeks answers