A mysterious outbreak among 10 Colorado children hospitalized for severe viral respiratory illness and later afflicted by
polio-like partial paralysis is “extremely unusual,” said the doctor directing the investigation.
The sudden appearance of so many cases of partial paralysis in one fairly small geographical region, the metro area, is a highly unusual manifestation of rare viral disease, said Dr. Mark Pallansch, director of the U.S. Centers for Disease Control and Prevention’s Division of Viral Diseases.
Compared with what investigators usually see — single cases or a cluster of two or three over many months or years — 10 is a big number, Pallansch said Tuesday.
The CDC is in the second week of its investigation of the 10 Colorado cases. The muscle-weakness cases have coincided with a statewide and national outbreak of an uncommon pathogen called enterovirus 68.
“It seems our cluster of cases in Colorado has some distinctive features,” Teri Schreiner said at a media briefing Tuesday. Schreiner is a pediatric neurologist at Children’s Hospital Colorado, where all of the cases were identified.
The Colorado cluster involves MRI findings of specific types of lesions in the gray matter of the spinal cord. Patient symptoms include muscle weakness that causes facial drooping, double vision and difficulties swallowing and breathing. Partial paralysis or extreme weakness also affects one or more limbs, sometimes all four, she said.
Six of the Colorado children had recovered sufficiently, although not completely, to be discharged from the hospital. Physicians said it wasn’t known if or when the children would have a full recovery from symptoms.
In a recent telephone conference with more than 20 specialists from most major cities, Schreiner said Children’s Hospital specialists heard of cases with some similar paralysis-like symptoms following respiratory illnesses.
“It’s hard to know if these are exactly the same thing,” said Children’s epidemiologist Sam Dominguez.
Officials at Boston Children’s Hospital said Tuesday they are treating four children with muscle weakness or paralysis that began soon after they were sick with a severe respiratory illness. None have tested positive for enterovirus 68.
In California, researchers found that two of five children who developed paralysis in their arms and legs in 2012 and 2013 tested positive for enterovirus 68. State health officials said there were 20 children whose respiratory illnesses developed into polio-like paralysis.
For some of those children, the sudden onset of flaccid or limp-limbed paralysis led to long-term, possibly permanent paralysis, said pediatric neurologist Keith Van Haren of Lucile Packard Children’s Hospital Stanford.
“The Colorado cluster is completely unprecedented both in its temporal and geographical features,” Van Haren said. It is a lot of cases occurring quickly in a small area, he said.
The California cases occurred sporadically around the state over years. This cohort also includes some adults.
Children’s Hospital Colorado has treated more than 4,000 children since Aug. 18 for enterovirus 68 and other cold viruses. About 10 percent of them, roughly 400, were hospitalized for severe respiratory illness, said Children’s infection specialist Christine Nyquist. Of those, 10 children developed spinal cord infection, also called myelitis. Statewide and nationwide, millions of children have been affected by the outbreak, but most suffered only mild cold symptoms.
Most of the 10 Colorado children had been previously healthy, but three had other medical conditions, including two with asthma and one heart transplant patient who was taking drugs to suppress immunity so the new organ wouldn’t be rejected.
Testing of the children for enterovirus 68 has been inconclusive. Nine were tested. None tested positive for the virus in their spinal cords. Four children’s nasal samples were positive for enterovirus 68. Two were positive for other viruses. One test result is pending.
But, the doctors said, the children might have been infected with the virus, and it simply wasn’t found or it had cleared up since the onset of the illness.
“It’s always difficult to prove causation,” Doming- uez said.
However, he said, they have ruled out a few other paralysis-causing viruses in the eight children tested, including West Nile, Guillain-Barre and polio.
Electa Draper: 303-954-1276, edraper@denverpost.com or twitter.com/electadraper
