Researchers found an alarming link between the enterovirus D68 (EV-D68) an unexplained cases of childhood paralysis.
The most cases of flaccid myelitis (unexplained muscle weakness and paralysis) took place during a nationwide outbreak of the severe respiratory illness EV-D68 that occurred in the U.S. last fall, the University of California, San Francisco reported. EV-D68 was seen in half of California and Colorado children diagnosed with acute flaccid myelitis.
A team of scientists looked at the genetic sequences of EV-D68 in children with acute flaccid myelitis, and found they corresponded with strain B1, which first emerged about four years ago and exhibited mutations similar to what is seen in poliovirus and the nerve-damaging virus EV-D70. The study also looked at a pair of siblings who were both infected with genetically-identical versions of EV-D68, but only one of whom experienced acute flaccid myelitis.
"This suggests that it's not only the virus, but also patients' individual biology that determines what disease they may present with," said Charles Chiu, an associate professor of Laboratory Medicine and director of UCSF-Abbott Viral Diagnostics and Discovery Center. "Given that none of the children have fully recovered, we urgently need to continue investigating this new strain of EV-D68 and its potential to cause acute flaccid myelitis."
Eighty percent of the 25 patients with acute flaccid myelitis in the study reported having upper respiratory illness about six days before suffering acute flaccid myelitis; a slightly higher percentage reported fevers during this time.
"The lack of detectable virus in CSF could also mean that the neurological symptoms are coming from an aberrant immune response to recent EV-D68 infection and not because the virus is directly invading neurons," Chiu said.
The study was supported by grants from the National Institutes of Health, a University of California Discovery Award, an Abbott Viral Discovery Award and the Centers for Disease Control and Prevention Emerging Infections Program.
