Is Outbreak of Polio-Like Disease Statistical Noise or Looming Threat?

Thursday, March 06, 2014

Doctors are baffled by a polio-like paralysis that has struck up to 25 California kids. It has been dismissed by some as a statistical anomaly that just happened to draw media attention, but the link of at least a few of the cases to a polio-like virus has sent chills through the public health community.

The story first surfaced when doctors at two institutions, Lucile Packard Children's Hospital at Stanford University and the University of California San Francisco Medical Center, noted that five of their patients had shown the quick polio-like onset of paralysis in a limb during the past year. Two of the children tested positive for enterovirus-68 (EV68), which is in the same Picornaviridae family of viruses as polio.

Despite the familial link, EV68 rarely becomes more serious than a cold, although it can cause meningitis and encephalitis. All five of the kids, ages 2 to 16, had been vaccinated for polio. They live within a 100-mile radius of each other, but no common factors have been established between them.

The doctors reviewed all polio-like cases in the state from August 2012 to July 2013 and found between 20 and 25 that seemed to constitute a cluster of disease. But the cases have not yet been linked to EV68 or, for that matter, to each other although the disease is contagious. Researchers do not know the cause of the paralysis, which is apparently permanent, and say the presence of EV68 may just be incidental.

None of the children died. Polio strikes swiftly with often devastating and permanent effect, but is usually not fatal.

Jane Seward, at the federal Centers for Disease Control and Prevention (CDC), told National Geographic, “We’re not considering this an outbreak.” The deputy director for the division of viral diseases said a small number of such cases, where paralysis is sudden, happen every year. “At this time we don't think the situation in California is a cause for public concern,” she said.

Keith Van Haren of Lucile Packard Children's Hospital sounded less assured. “Normally, you'd expect to see this kind of case once every five years,” he said, calling it “a modest increase of a very rare syndrome.” Emmanuelle Waubant at the UC San Francisco Medical Center said, “We don't think that there is an epidemic about to hit.”

Although it has been 60 years since polio ravaged the country, paralyzing 35,000 American kids a year in the 1950s, the memory and fear of it has not disappeared. The disease stretches back into pre-history but it wasn’t until European epidemics in the late 19th Century that the world took notice. Epidemics appeared with regularity through the 20th Century but were brought under control in industrialized nations in the 1960s.

Polio has been eradicated from most of the world but remains endemic in Pakistan, Afghanistan and Nigeria. In 2009, fewer than 2000 cases were reported for the entire year.     

–Ken Broder 


To Learn More:

California Mystery Disease Is Like Polio—But It's Not Polio (by Diane Cole, National Geographic)

Polio-Like Illness Seen in up to 25 California Children (by Laila Kearney, Reuters)

Polio-Like Disease Appears in California Children (by Martha Mendoza, Associated Press)

Mysterious Polio-Like Illness Found in Five California Children (American Academy of Neurology)

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