A new study by researchers from Children’s Hospital Colorado suggests a potential link between a rare respiratory virus and a form of paralysis that has so far affected more than 100 children in the US.

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Researchers say there may be a link between enterovirus D68 and cases of AFP that have affected more than 100 children in the US.

Since early August last year, 107 children over 34 US states have developed acute flaccid paralysis (AFP) – a sudden form of muscle weakness or paralysis. The condition is characterized by limb weakness, difficulty swallowing and/or facial weakness.

AFP is normally associated with poliovirus, and global vaccinations for the virus has meant incidence of AFP has become uncommon. But the number of recent cases identified is three times higher than normal.

While the cause remains unclear, the Centers for Disease Control and Prevention (CDC) have flagged enterovirus D68 (EV-D68) – a non-polio virus that causes mild to severe respiratory illness – as a culprit, particularly since 2014 saw an outbreak of the virus around the same time as cases of AFP rose.

Starting in Missouri and Illinois in August 2014, outbreaks of EV-D68 soon started to spread to other parts of the US, including Colorado – where from then until October, several children were admitted to Children’s Hospital Colorado with AFP.

Study leader Dr. Kevin Messacar, a pediatric infectious disease physician and researcher at Children’s Hospital Colorado, and colleagues set out to review these cases in an attempt to gain a better understanding of the cause.

According to the researchers, between August 1st and September 30th, 2014, there was a 36% rise in the number of respiratory-related visits to Children’s Hospital Colorado emergency department and a 77% increase in respiratory-related admission rates, compared with the same months in 2013 and 2014.

During the same period last year, the team notes, there was also a significant rise in the number of nasal samples testing positive for rhinovirus and enterovirus.

“In a sample of 25 specimens from children admitted to the intensive care unit with severe respiratory illness who tested positive for rhinovirus or enterovirus in the nasopharynx, we identified EV-D68 in 19 (76%) specimens,” say the researchers.

Between August 1st and October 31st, 2014, the researchers identified 12 children who presented at the hospital with varying severities of muscle weakness in their limbs, facial weakness and problems swallowing. Around a week before these symptoms started, all of the children had a fever and respiratory illness.

Magnetic resonance imaging (MRI) revealed that 10 of the children had lesions in the spinal cord, while nine of the children had brain stem lesions. The researchers identified the presence of enteroviruses or rhinoviruses among eight of the children – and five of these tested positive for EV-D68.

Though the 12 children have received treatment, 10 of the children with limb paralysis continue to have problems and the researchers say it is unclear as to whether this will be permanent. They add that three of the children have shown improvements in swallowing and facial weakness, however.

Based on their findings, published in The Lancet, the researchers believe it is possible EV-D68 may be associated with neurological disease. They say:

We report the first geographical and temporal cluster of acute flaccid paralysis and cranial nerve dysfunction associated with a community-wide outbreak of enterovirus-D68 respiratory disease.

Although our findings do not prove that enterovirus D68 is the cause of the neurological presentations described, several epidemiological, virological and clinical factors suggest an association between the D68 virus and neurological disease.”

They add that if EV-D68 outbreaks continue, effective treatments and vaccines against the virus need to be a major scientific priority.

“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,” says senior author Dr. Samuel Dominguez, microbial epidemiologist at the Children’s Hospital Colorado.

In June 2013, Medical News Today reported on a study that found a number of children with Crohn’s disease also had enterovirus, indicating a link between the two conditions.