The CDC is investigating a cluster of 9 Colorado cases of what sounds like acute flaccid paralysis, possibly associated with enterovirus D68. EV-D68 infections are on the rise nationwide and are causing severe respiratory illness and possibly some deaths. Some of the neurological patients tested positive for EV-D68 and negative for both polio virus and the virus now most commonly associated with acute flaccid paralysis (answer after the jump). The patients all had MRIs showing gray matter disease, but I couldn’t find any pictures online. My guess is that they look something like this:
Note in the axial image how the signal hyperintensity is confined to the gray matter, making it a poliomyelitis rather than a transverse myelitis. (I think the term poliomyelitis is usually reserved for cases caused by the polio virus. My understanding, though, is that polio is derived from the Latin word for gray, so poliomyelitis is actually a descriptive term).
The CDC case definition and reporting form can be found here.
And the most common cause of acute flaccid paralysis is . . .
. . . West Nile virus (WNV). I think it’s worth pointing out that even if EV-D68 is the cause of these polio-like cases, it’s likely that, as with WNV, only a very small percentage of infected people will develop neurological illness.