February 28, 2018
Since 2014, doctors have been stymied by a medical mystery: People, mostly children, were coming down with a previously unknown, polio-like illness that causes paralysis. Now, an international team of doctors published in The Lancet believe they’ve managed to confirm the main culprit.
Ever since the defeat of polio in the U.S. a half-century ago, reported cases of paralysis brought on by infection had been virtually non-existent. Mosquito-borne germs, like West Nile virus, are known to trigger a polio-like paralysis, while others can cause a rare autoimmune complication called Guillain-Barré syndrome, but neither happen with any regular frequency. Starting in 2014, though, doctors started seeing a spate of children suffering an acute and rapid weakening of their muscles and paralysis, primarily affecting the limbs, along with confirmed spinal cord damage. That year, there were 120 confirmed cases of this acute flaccid myelitis, as it’s formally known, found across 34 U.S. states, while 2016 saw 149 cases across 39 states. Several deaths have also been linked to the condition.
The afflicted children had little in common, except that some seemed to have been infected by an airborne virus related to polio known as Enterovirus D68 just before falling ill. EV-D68 infection had long been thought to cause nothing more than the common cold, and there had been only 26 reported cases of it in the U.S. from 1970 to 2005, following its initial discovery in the early 1960s. But both 2014 and 2016 had large outbreaks of EV-D68 that occurred around the same time that clusters of AFM were detected, while 2015 saw almost no cases of either the virus or the condition. And there’s been evidence that cases have stretched as far back as 2012.