The CDC is investigating 180 cases of children with hepatitis. The cause is a mystery

The Centers for Disease Control and Prevention says it's investigating 180 pediatric patients with hepatitis of unknown cause. The cases, which have included five deaths, have been reported in 36 states and territories over the past seven months.

The count of cases under investigation has grown since the CDC's last update on May 5, when the agency said it was investigating 109 cases. But the agency said that most of the latest cases are "retrospective" cases — the CDC's investigation involves reported cases that date back to October 2021, and many of them are just now being reported.

Hepatitis is characterized by a swelling of the liver. The proportion of affected patients requiring liver transplants has declined from 15% to 9% since May 5, according to the CDC. Earlier this month, the CDC reported that five children have died; the agency now says that no additional deaths have been reported since February.

The CDC is advising parents and caregivers to be aware of the symptoms, including jaundice in particular. They should contact health care providers with any concerns.

The CDC is examining possible causes of the cases. Adenovirus, a common virus that often causes mild cold or flu-like symptoms, has been identified in almost half of the pediatric patients with hepatitis. The CDC said other tests are being conducted to look at other "potential pathogens," including the coronavirus.

"It's important to note that severe hepatitis in children remains rare," the agency said.

The agency said it will begin posting weekly updates on the number of patients under investigation.

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