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.”
But after we saw 149 cases in 39 states in 2016, there were only 33 cases in 16 states in 2017.
And there have been about 38 cases in 16 states in 2018, coming out of the peak season for AFM cases – August to October.
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.
It is important to note that only some, but not all, of the kids with AFM have been positive for enterovirus D68. In Colorado this year, 9 of 14 cases were linked to EV-A71 infections.
Acute Flaccid Myelitis
What is 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 350 children 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.”
AFM isn’t caused by vaccines though…
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
- Why health care providers & public health professionals say vaccines are not the cause of recent acute flaccid myelitis (AFM) cases
- Polio-like syndrome – blame enterovirus 68 not vaccines
- Acute flaccid paralysis of unknown etiology in California
- WHO-recommended surveillance standard of poliomyelitis
- Polio-like paralysis in California
- CDC cites 2 more deaths in EV-D68 cases, more polio-like illnesses
- Study – Enterovirus D68 and acute flaccid myelitis-evaluating the evidence for causality.
- AAP – No common etiology, treatment found for acute flaccid myelitis
- CDC – About Acute Flaccid Myelitis
- CDC – AFM Investigation
- Transverse Myelitis Association
- Six Minnesota kids suffer rare, polio-like disorder
- States and CDC probe reports of rare poliolike symptoms in kids
Updated November 13, 2018
Last Updated on November 14, 2018 by Vincent Iannelli, MD