Polio has been in the news a lot lately.
Well, not exactly polio.
The term “polio-like” has been in the news.
This follows a large outbreak of enterovirus D68 (EV-D68) respiratory infections in 2014, some of which seemed to be associated with the development of acute flaccid myelitis (AFM).
While there were no reports of EV-D68 infections in 2015, there have been “limited sporadic EV-D68 detections in the U.S. in 2016.”
Similar to coxsackievirus, which causes hand, foot, and mouth disease, EV-D68 is a non-polio enterovirus. On the other hand, the virus that actually causes polio is just a different type of enterovirus.
Because they are all enteroviruses, some get differentiated as being non-polio.
To make it even more confusing, some non-polio enteroviruses can cause a polio-like syndrome. And both polio and non-polio enteroviruses can cause acute flaccid myelitis.
Acute Flaccid Myelitis
AFM is a syndrome characterized by sudden onset of limb weakness, sometimes accompanied by cranial nerve dysfunction (such as facial drooping or difficulty speaking). In many cases, distinctive lesions in the gray matter (nerve cells) of the spinal cord may be seen on neuroimaging.
Acute flaccid myelitis caused by the polio virus can usually be recognized because it is associated with an unvaccinated person who traveled to an area that still has cases of polio and who has “one or more limbs with decreased or absent tendon reflexes in the affected limbs, without other apparent cause, and without sensory or cognitive loss. Paralysis usually begins in the arm or leg on one side of the body (asymmetric) and then moves towards the end of the arm or leg (progresses to involve distal muscle groups).”
Since 2014, at least 230 children in 34 states have developed acute flaccid myelitis. Most had some improvement in function and a small number had a complete recovery, just as a small number had no improvement.
And of course, none of them had polio. In fact, the last polio outbreak in the United States was in 1979.
So maybe we should stop saying “polio-like,” as it likely just confuses people, few people likely know what “polio-like” symptoms actually are, and these cases have nothing to do with the polio virus.
Unfortunately, “despite extensive testing, CDC does not yet know the cause of the AFM cases.”
Still, the CDC recommends standard precautions to try and avoid AFM, including handwashing, avoiding other people who are sick, getting vaccinated (to avoid polio), and protecting your kids from mosquitoes (West Nile virus can cause AFM too).
For More Information on Polio-Like Syndromes
- CDC – Enterovirus D68
- CDC – About Acute Flaccid Myelitis
- CDC – AFM in the United States (2016)
- The Mysterious Polio-Like Disease Affecting American Kids
- Polio-like illness emerging in California – not vaccine related