(CNN) — A mysterious polio-like illness has been found in five children in California, researchers said.
The discovery is alarming because polio, a contagious disease that sometimes caused paralysis, was wiped out in the United States in 1950s after a vaccine was created. All five children had polio vaccinations.
The new cases, the researchers say, point to the possibility that an “infection polio-like” syndrome could be emerging in California.
Dr. Keith Van Haren of Stanford University and his co-author, Dr. Emanuelle Waubant with the University of California-San Francisco, released a case report on their findings Sunday. They will present the report at the American Academy of Neurology meeting in April.
“Although polio virus has been eradicated from most of the globe, other viruses can also injure the spine, leading to a polio-like syndrome,” he said in a statement.
Outbreaks of polio have occurred in Pakistan, Nigeria and Afghanistan.
Van Haren and Waubant said the five children showed polio-like symptoms: sudden paralysis in one or more limbs that became most severe within two days of onset.
Three children had a respiratory illness before the other symptoms began, they said. After treatment, the symptoms didn’t improve and the children still had poor limb function after six months.
Two children tested positive for enterovirus-68, a rare virus previously associated with polio-like symptoms, they said. No cause was identified in the remaining three children.