Doctors at Cincinnati Children’s Hospital in Ohio say they have treated at least six cases of severe hepatitis in previously healthy toddlers ages 18 months to 10 years. One required a liver transplant.
These cases add to a growing number of puzzling reports of young children around the world developing acute hepatitis without a known cause.
Dr. Jorge Bezerra, director of the Pediatric Liver Care Center at Cincinnati Children’s Hospital, said his team has seen an increasing number of these patients since December.
“We’ve seen six,” Bezerra told NBC News on Wednesday. “Today we are going to see a seventh patient,” she said. “They are still coming.” The children treated for liver disease at Cincinnati Children’s are all from Ohio.
No one has been able to figure out why these children develop hepatitis, which simply means inflammation of the liver.
“There is no link to a geographic area, common exposure to particular foods or animals, travel, or toxins,” said Dr. Philippa Easterbrook, an infectious disease physician at the World Health Organization, during a news conference on Wednesday.
At least 228 such cases have been reported in 20 countries, it said. Ten percent of children have required liver transplants.
Related: First child dies in severe hepatitis outbreak in 12 countries
The usual suspects, hepatitis A through E viruses, have been ruled out. Children do not present with evidence of COVID-19, and most are too young to have received COVID-19 vaccinations.
Many, but not all, children have tested positive for an adenovirus.
Adenoviruses can cause a variety of symptoms, from colds to diarrhea and, in rare cases, hepatitis. Those extreme cases are usually found in children with underlying health problems or immune deficiencies, Bezerra said.
But otherwise, the children treated at Cincinnati Children’s are in good health.
“We’re all putting our heads together to try to understand what’s going on,” Bezerra said.
At least nine other states have suspected cases: Alabama, Delaware, Georgia, Illinois, Louisiana, New York, North Carolina, Tennessee and Wisconsin.
Wisconsin officials are investigating the death of a child.
Cases began appearing in Alabama last October. Bezerra said his Ohio team is now reviewing cases that may have been filed as early as June 2021.
“I think I’m finding that the number of patients is going to exceed 10,” he said.
Bezerra sees about 10 of these patients in a typical year. “Having seven to 10 in the first quarter of the year is higher than usual.”
In April, the Centers for Disease Control and Prevention issued a health alert so doctors across the country could be on the lookout for these rare cases of pediatric hepatitis.
Apart from liver transplantation in extreme cases, there is no specific treatment for affected children. They usually need to be monitored and supported with proper hydration and nutrition so their liver has time to heal.
Doctors say that patients usually have vomiting, as well as mild abdominal pain, diarrhea, fever and nasal congestion.
Those symptoms, however, are quite common in young children who routinely develop stomach viruses.
But Bezerra said if those symptoms last more than a few days and are accompanied by yellowing of the skin and eyes, it’s time to call the doctor.
“The most important thing is, if there is an onset of jaundice or yellow discoloration of the eyes,” he said, “seek medical help.”
This story first appeared in NBCNews.com.