Polio-like disease

This is a post relevant to something happening now in California. Over a period of eighteen months, we've had an increase in children how are experiencing an acute chronic, focal (isolated or localized, such as to a limb) paralysis. Described as 'Polio-like disease' because of its clinical presentation, we know that this is NOT Polio because all of the afflicted children have been vaccinated, Polio no longer circulates naturally in the US, and no Polio samples have been recovered from any of the kids. The paralysis is, as of yet, of an unknown cause, and has afflicted around twenty children.[2] Two of the children have tested positive for a Picornavirus (same family as Polio) that's been known to be circulating since the 60's- Enterovirus 68. Stanford doctors suggest that they're suspicious for this virus as the causative agent, since three children were known to have respiratory illness before developing paralysis, and EV68 is a respiratory pathogen. Also, two of the children were found to have EV68 in their stool.

Personally, I'm not convinced that EV68 is the culprit here. There've been multiple outbreaks of EV68 as a respiratory pathogen since we've known about it, with no neurological effects reported in any of them.[1] It's true that viruses mutate, but I'm sure that we would've seen neurological effects before now in some of the other outbreaks. We know the EV68 circulates naturally in California, and that the virus must be spreading through a population in order to not go extinct. No epidemiological control measures have been taken to my knowledge. What that means is that the virus should still be circulating. If the virus did mutate to become neurovirulent, we should be seeing a lot more cases of the 'Polio-like disease' very soon. I don't expect that to happen, but we'll see.

What's more is that the sample size is very small- only 20 kids- and the sample size with EV68 is even smaller- only two kids. The evidence is so circumstantial, and I think it would be almost as solid to blame influenza. Not to mention that the CDC is presently investigating, and has not spoken to the EV68 hypothesis at all. I'm not saying that it's not EV68, but I'm saying that we don't need to prematurely jump on a pathogen and end up barking up the wrong tree, especially if this does turn into a pandemic- which the numbers seem to argue against by their slow accumulation. 

Vincent Racaniello, host of This Week in Virology and Virology professor at Columbia University has had extensive experience working with Polio and Picornaviruses. On his blog at Virology.ws he argued that California normally has about 70 cases of 'polio-like disease' per year, and that the present number of cases mentioned in the alleged outbreak don't exceed the normal background caseload. For a much more informative article, his blog is worth your time, check it out. If you're concerned about this illness, watch your kids for any signs of sudden, enduring, limp limb paralysis or weakness and report to your doctor immediately if you see anything. If your kids need the polio vaccine, continue receiving it, since Polio is still out and about in the world. There are no special precautions or actions that should be taken otherwise.

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[3]Virology.ws

[2]http://healthier.stanfordchildrens.org/q-rare-polio-like-disease-emerges-california/

[1]http://www.medscape.com/viewarticle/751032_1