2014 Polio-Like Paralysis Update: Acute Flaccid Myelitis Might Not Have Been From Enterovirus D68

In the summer of 2014, a mysterious outbreak of polio-like paralysis stumped infectious diseases specialists, with scientists and doctors leaning towards blaming enterovirus D68 for the sudden cases of acute flaccid myelitis that followed some U.S. children's cold-like symptoms.

Initial symptoms included a cough, headache, and slight fever. But when a 6-year-old girl was brought to the University of Virginia's Children's Hospital with all the same symptoms as the children thought to have been plagued by enterovirus D68 had, doctors revealed that the polio-like paralysis outbreak of 2014 might not have been the culprit after all.

The 6-year-old girl's tests came back with a different suspect: Enterovirus C105.

"Surprisingly, it came back with this enterovirus C105, which I'll admit, when it came back, I'd never heard of," UVA's Dr. Ronald B. Turner, explained of the 6-year-old girl's tests.

"It was just described in the last eight or nine years and it hasn't been seen much around the world. Now, I think you have to be careful with that, because we don't look for it. And you don't see what you don't look for. So it's possible it's out there and it's not being detected because nobody's sending specimens to be tested in this way."
Enterovirus D68 was only detected in eight of the 41 children exhibiting the polio-like paralysis, according to Medical News Today. Turner and his colleagues suggest that perhaps Enterovirus D68 took the blame simply out of coincidental timing. Perhaps those children suffering from paralysis tested for Enterovirus D68 simply because it was going around at the same time as the genuine culprit, which Turner says could actually be C105.
"Because of the temporal relationship, a lot of people connected those two events and basically assumed that the enterovirus D68 was somehow related to the acute flaccid paralysis."
"You can only learn so much from one case. My plea is that we not over-interpret this information," he said.

"We need to kind of step back and say, 'OK, we really don't know what's going on here,' " Turner said after the UVA doctors published the 6-year-old's case study in the journal Emerging Infectious Diseases, authored by Liana M. Horner, Melinda D. Poulter, J. Nicholas Brenton, and Turner.

Enterovirus C105 (EV-C105) was first identified in the Democratic Republic of Congo in late 2010, according to the World Health Organization. Initially, it was identified incorrectly, but it was first found in a fecal sample collected from a patient who died after suffering from acute flaccid paralysis with suspected poliomyelitis. The enterovirus C105 was identified as the cause of the patient's deadly polio-like paralysis. That patient acquired a lethal illness from the enterovirus right in the thick of an actual polio outbreak, but the patient did not have polio itself.

In November of 2010, the WHO said that the polio outbreak of 2010 in the Democratic Republic of Congo was caused by an imported poliovirus, so experts were taking extreme measures to track and control the outbreak, but fecal samples were collected from only a small percentage (16 percent) of paralysis or myelitis sufferers during that outbreak.

"The Government of Congo has alerted the public to the outbreak and launched an emergency response plan, with support from key partners, including WHO, UNICEF and the US CDC. At least three nationwide vaccination campaigns are expected, using monovalent oral polio vaccine and targeting the entire population."
The CDC reported on the polio situation in the Democratic Republic of Congo in March, 2011, stating that 554 acute flaccid paralysis cases were identified from September of 2010 to February of 2011. The polio vaccination records were only available for 149 of the 554 acute flaccid paralysis patients during that outbreak. Of the 149 patients with a known vaccination status, 72 percent of the patients experiencing paralysis received at least one dose of the oral polio vaccine, and 73 of those patients received at least three doses of the OPV. The CDC blamed that outbreak on relatively low vaccination coverage in the area, crowding of residents, poor water supply, poor sanitation facilities, suboptimal medical care, delays in seeking care, and the high proportion of cases among adults and teens -- a population which the CDC says are known to be at greater risk of death from poliovirus than young children and are "known to be at higher risk for bulbar paralysis than children."

As for the non-polio cases of acute flaccid paralysis in the U.S. in 2014, the experts at UVA stress that they have no certain answer in light of the new discovery of C105 and the fact that it is generally not tested for. Turner said of the UVA publication, "It was really just an attempt to say, 'Hey wait a minute, there are other possibilities for what's going on with this flaccid paralysis and we need to keep an open mind about this.'" After all, there could be multiple causes of polio-like acute flaccid paralysis and myelitis in any given disease outbreak, like experts saw in the Democratic Republic of Congo.

Could it have been enterovirus C105 that was actually to blame for the polio-like paralysis that terrified parents across the nation last year and not D68?

[Photo credit: U.S. CDC]