Ten Colorado children with mystifying muscle weakness and partial paralysis are still suffering symptoms and may be permanently disabled, doctors reported Wednesday.
The strange set of symptoms is linked to a normally harmless cold virus called enterovirus D-68 or EV-D68. For some reason, the virus caused an outbreak this past fall, and more than 100 children have since been diagnosed with a side-effect called acute flaccid myelitis or acute flaccid paralysis (AFP for short).
Most doctors hadn't seen anything like it since polio was virtually eradicated. EVD-68 is a distant relative of polio, and of another enterovirus called EV-A71 that has been known to occasionally cause the paralytic syndrome.
"The extent to which this new distinctive neurological disease has spread is unknown."
But the recent rash of cases is triple the usual number and may be the tip of the iceberg, says Dr. Samuel Dominguez, a microbial epidemiologist at the Children's Hospital Colorado.
"The extent to which this new, distinctive neurological disease has spread is unknown, but it does not appear to be isolated to Colorado or the USA," Dominguez said in a statement.
"Since the reporting of this cluster, 107 similar cases have been reported across the USA and one in France," he added.
Seven-year-old McKenzie Andersen of Portland, Oregon is one of them. She caught a cold just before Christmas but became mostly paralyzed from the neck down within 12 days. She can wiggle her left hand, her feet and use facial muscles.
"She got a cold and now she's never going to walk again. How do you ever get your mind around that? This is so brutal, so devastating and so hard to understand," McKenzie's mother, Angie Andersen, told TODAY.
It's not yet clear whether this was a random outbreak or the beginning of an ominous pattern, Dominguez and colleagues said. But the cranial nerve damage is unusual and frightening.
"If further investigation confirms the link between EV-D68 and AFP and cranial nerve dysfunction, EV-D68 will be added to the list of non-poliovirus enteroviruses capable of causing severe, potentially irreversible neurologic damage, and finding effective antiviral therapies and vaccines will be a priority," they wrote in the Lancet medical journal.
They describe 12 children who were partly paralyzed between August and October.
"Over the past four years, our hospital has seen a maximum of four similar cases in any three-month period where children lose the use of one or both arms or legs. These 12 cases are three times that," Dominguez said.
Usually, the paralysis — which can cause trouble breathing in the most frightening cases — has been caused by enterovirus A71 or West Nile virus, which is transmitted by mosquitoes. But in five of the cases, recorded between August and October, the kids were infected with EV-D68. Others had a common cold virus called rhinovirus.
That doesn't mean EV-D68 wasn't involved in the other cases. The virus can disappear quickly from the body even if it leaves long-term damage behind it, the doctors said.
No treatment seemed to help. Some of the kids got plasma treatment, others were given an antibody treatment called gamma globulin. Both are meant to rev up the immune reponse. Two also got an experimental polio drug called pocapavir. "There was no evident short-term improvement after treatment with any of the above therapies," Dominguez and colleagues wrote.
"Despite treatment, all ten children with limb weakness still have ongoing problems and it is not known if the paralysis will be permanent. Three children have shown improvement in cranial nerve dysfunction (facial weakness and/or difficulty swallowing)," they added.
"Despite treatment, all ten children with limb weakness still have ongoing problems and it is not known if the paralysis will be permanent."
"Mild improvement in limb weakness has been noted in some children with physical therapies; however, all these children have persistent motor deficits. Long-term follow up of these children is crucial because improvement in motor function after acute flaccid paralysis, when it happens, can be delayed."
It might be that this is a rare complication of EV-D68, they said — and noted that tests have only recently become available for common use that can even tell doctors what kind of respiratory virus a patient has.
"Last, acute flaccid paralysis and cranial nerve dysfunction associated with enterovirus D68 might truly be a new occurrence indicating a newly emerged strain, viral mutation, or viral recombination," they said.
