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Rare polio-like illness could have affected up to 25 children

A polio-like illness may have affected up to 25 children in California, leading to the paralysis of some limbs, according to researchers.

Doctors are still not sure what caused this illness; some of the children involved have been found to have enterovirus 68, a rare virus associated with respiratory illness.

A report about five of the cases was authored by Keith Van Haren, a pediatric neurologist at the Lucile Packard Children’s Hospital at Stanford University, along with Emmanuelle Waubant, a neurology professor at the University of California in San Francisco. The report will be presented at the American Academy of Neurology’s annual meeting in Philadelphia (which runs April 26 to May 3).

Waubant said Tuesday that over the past year and a half, the two doctors have seen five cases, with children ranging between ages 2 and 16. There are also another 15 to 20 cases that have been reported to public health officials, although those have not been reviewed yet to see if they are suffering from the same illness, she said.

The illness is worrisome, not in the least because doctors haven’t found a common cause.

“This is not a cluster in that the cases were not all grouped together,” Waubant said. “These children have nothing in common.”

Polio is what’s known as an enterovirus, but there are also plenty of what are called non-polio enteroviruses. (The most well-known non-polio enterovirus might be hand, foot and mouth disease.) These viruses are very common in the United States, infecting about 10 to 15 million people each year, said Jane Seward, deputy director of the viral diseases division at the Centers for Disease Control and Prevention.

“Most enterovirus infections are mild and maybe even asymptomatic,” Seward said. “This is a very rare outcome.”

Seward said that the CDC is ready to conduct any tests or do any consulting as needed.

“We are taking this seriously and making sure that we’re doing our best to collect all the information that’s needed on these cases and to also make sure that, if there are additional cases, they will be identified promptly,” Waubant said.

Two of the five children in the case report tested positive for enterovirus 68. Some of the children had had a benign upper respiratory infection a few days before they began experiencing severe weakness in at least one limb, Waubant said.

The exact symptoms varied in the five children, with some feeling weakness in only one limb and others having more widespread weakness. One patient had to have a tube inserted for a few days to help her breathe, Waubant said. And recovery for the initial five cases “has been poor so far,” she said.

All five children included in the case report were vaccinated, Waubant said, though she doesn’t know yet about the other 15 to 20 cases.

Waubant said there aren’t concerns about an outbreak. Seward agreed, pointing out that a certain number of cases of acute flaccid paralysis (AFP) are expected each year.

Surveillance of AFP, considered a vital part of the fight to eliminate polio, should find at least one case of non-polio AFP each year per every 100,000 children younger than age 15, the Global Polio Eradication Initiative says. (“If you don’t see cases of paralysis, you’re not looking hard enough, because they happen all the time,” Seward said.) There were 8.1 million children under the age of 16 in California in 2010, according to this report.

“Within that context, the number of cases we’re aware of is not a cause for public concern,” Seward said, although she added that there’s still concern for the children involved.

Even though the polio vaccine wouldn’t prevent a child from contracting this illness, Steward stressed that it’s still important that people get vaccinated.

“We remain at risk of importation,” she said. “So if people aren’t vaccinated against polio, and they travel overseas to areas where polio is still endemic … they’re at risk of getting polio and polio could come back into this country.”