SOURCES: Kevin Messacar, M.D., pediatric infectious diseases physician, Children's Hospital Colorado, Aurora; Amesh Adalja, M.D., senior associate, University of Pittsburgh Medical Center, Center for Health Security, and spokesman, Infectious Diseases Society of America; Jan. 29, 2015, The Lancet
THURSDAY, Jan. 29, 2015 (HealthDay News) -- A cluster of 12 Colorado children are suffering muscle weakness and paralysis similar to that caused by polio, and doctors are concerned these cases could be linked to a nationwide outbreak of what's usually a rare respiratory virus.
Despite treatment, 10 of the children first diagnosed late last summer still have ongoing problems, the authors noted, and it's not known if their limb weakness and paralysis will be permanent.
The viral culprit tied to at least some of the cases, enterovirus D68 or EV-D68, belongs to the same family as the polio virus.
"The pattern of symptoms the children are presenting with and the pattern of imaging we are seeing is similar to other enteroviruses, with polio being one of those," said lead author Dr. Kevin Messacar, a pediatric infectious diseases physician at Children's Hospital Colorado in Aurora.
Dr. Amesh Adalja is a senior associate at the Center for Health Security at University of Pittsburgh Medical Center, and a spokesman for the Infectious Diseases Society of America. He stressed that it's "important to keep in context that this is a rare complication that doesn't reflect what enterovirus D68 normally does in a person.
"There's no avoiding comparisons to polio because it's in the same family of virus, but I don't think we're going to see wide outbreaks of associated paralysis the way we did with polio," Adalja added. "For whatever reason, we're seeing a smaller proportion of paralytic cases."
In 2014, the United States experienced a nationwide outbreak of EV-D68, according to the U.S. Centers for Disease Control and Prevention (CDC). From mid-August to mid-January 2015, public health officials confirmed more than 1,100 cases in all but one state. The virus was detected in 14 patients who died of illness, the CDC reported.
In most cases EV-D68 resembles a common cold, according to the CDC. Mild symptoms include fever, runny nose, sneezing and cough. People with more severe cases may suffer from wheezing or difficulty breathing.
Colorado was hit hard by EV-D68, the report authors say in background notes. In August and September, Children's Hospital Colorado experienced a 36 percent increase in ER visits involving respiratory symptoms and a 77 percent increase in admissions for respiratory illness, compared to 2012 and 2013.
During that same time frame, the hospital also began to see children come in with mysterious limb weakness and paralysis. A review of cases between August and October revealed 12 children, averaging 11.5 years of age, who had suffered these symptoms.
The children all had varying degrees of muscle weakness to the arms and legs, difficulty swallowing, and/or facial weakness. In addition, all had a fever and respiratory illness about a week before the neurological symptoms began, according to the study.
Doctors found that 10 of the children had spinal cord lesions revealed by MRI, and brainstem lesions were seen in nine children.
Eight of the children tested positive for enteroviruses or rhinoviruses, of which five were identified as EV-D68. Eleven of the children had been previously vaccinated against polio. One child was completely unvaccinated, according to the study.
Messacar said he and his colleagues wanted to raise the possibility of a link between these cases and the EV-D68 outbreak, although he added, "We can't definitively prove the two are linked."
There is currently no vaccine available for EV-D68, and no antiviral medications have yet been identified as effective in treating the virus, Adalja said.
Doctors at Children's Hospital Colorado tried a variety of treatments, including the antiviral drug pocapavir, and none seemed to help the children, according to the study.
"People are looking into which compounds might be active against it in the future," Messacar said.
Other cases have arisen across the United States. McKenzie Andersen, a 7-year-old girl from Portland, Ore., contracted a virus in December and is now largely paralyzed from the neck down.
"She got a cold and now she's never going to walk again," McKenzie's mother, Angie Andersen, told NBC News. "How do you ever get your mind around that? This is so brutal, so devastating and so hard to understand."
Parents who want to protect their children from EV-D68 and other ills should teach their kids to wash their hands often and follow other good hygiene habits, like covering their cough, Messacar and Adalja said.
The outbreak of EV-D68 has ended for now, following the usual trend of enteroviruses to come in the late summer and early fall and then fade away by winter, Messacar said.
No one can say if EV-D68 will reappear next year, as it hasn't yet established a pattern of infection, he said.
"That's the next big question -- is this something that happened as a fluke, or something that's going to come back for years to come?" Messacar said. "We want to be prepared if it comes back."
A report detailing the Colorado children's illnesses was published Jan. 29 in The Lancet.
For more information on enterovirus D68, visit the U.S. Centers for Disease Control and Prevention.