A rare “polio-like syndrome” has caused paralysis in about 20 children from across California, according to a report released Sunday by physicians in the San Francisco Bay Area.
The children, who are between the ages of 3 and 12, developed what is called acute, or sudden, flaccid paralysis — weakness or loss of muscle tone resulting from injury or disease of the nerves that stimulate muscles to move.
Although polio has been wiped out across most of the globe, other viruses can injure the spine, causing paralysis, said Dr. Keith Van Haren, author of the case report and a pediatric neurologist at Lucile Packard Children’s Hospital, at Stanford University. The children who have been affected seem to have been permanently paralyzed, he said.
Van Haren said these cases suggest there is a possibility of a new infectious polio-like syndrome in California.
The illness is not polio. All the victims had been immunized against polio and tested negative for the presence of the disease, Van Haren explained. And the disease is rare. “It’s not an epidemic,” he said. “But it is something that is concerning.”
The culprit could be a virus strain called enterovirus-68 that has been linked to polio-like outbreaks in children in Asia and Australia, Van Haren said. But not all of the victims tested positive for that virus, so the cause of the disease is still unclear.
Some of the children had respiratory or other illnesses before developing muscle paralysis, but for others muscle weakness was the first symptom.
Van Haren said some victims suddenly developed weakness of one or more limbs within about 48 hours of becoming sick. MRI scans showed worrisome changes in the gray matter of the spinal cord.
To help them more effectively fight the disease, the children were given steroids, intravenous immunoglobulin and/or blood plasma exchange — without improvement, according to the authors of the case report.
How was the mysterious illness discovered? Van Haren said that after he cared for four of five of the first cases that appeared in 2012, he realized the children’s illnesses and resulting paralysis were highly unusual. He notified the California Department of Public Health, which has helped monitor the outbreak since.
Van Haren and his team reviewed all five polio-like cases among children whose lab samples had been referred to California’s Neurologic and Surveillance Testing Program from August 2012 to July 2013. He has now included the data from about 15 additional cases reported since then, which he’ll be presenting at the American Academy of Neurology annual meeting, held April 26 to May 3 in Philadelphia.
Flaccid paralysis — unlike measles or pediatric flu deaths, for example — is not considered a disease or condition that must be reported to county or state health departments or national agencies like the U.S. Centers for Disease Control and Prevention.
Because there is no reporting requirement, the scope of the problem is still hard to assess, explained Dr. Carol Glaser, chief of encephalitis and the special investigations section in the California Department of Public Health. “We do not know whether these cases represent an increase in cases over what usually occurs or even if cases are an ongoing or isolated occurrence,” she said.
Glaser also pointed out that the California Department of Public Health has not yet identified a common cause for the cases. “At this stage, CDPH has asked health care providers to report any polio-like cases they might identify and send specimens so that we can better assess the situation,” she said.
On a national level, the CDC also cannot know for sure whether there are more cases of this polio-like syndrome than they have heard about, or to what event the illness may be appearing in other states. “It’s hard to know if five or 20 cases in the course of a year or two are significant,” said Jason McDonald, CDC spokesperson. “Acute flaccid paralysis can be the result of a variety of viral and non-viral causes.”
Parents who notice a sudden onset of weakness in their children should see their pediatrician right away, Van Haren advised. Physicians in the state should notify the California Department of Public Health any time they see a child with acute flaccid paralysis that is not due to diseases that affect the nervous system, such as botulism or Guillain-Barre syndrome, he added.
For her part, Glaser emphasized that only a very small number of cases have been identified, with no clear common cause. “Health care providers have been asked to send information about similar cases so that we can determine whether or not there is anything unusual about these cases,” she said.
Because this case review has not yet been published in a peer-reviewed journal, the data and conclusions should be viewed as preliminary, CDC’s McDonald cautioned.
Learn more about non-polio enteroviruses from the U.S. Centers for Disease Control and Prevention.