Acute Flaccid Myelitis in the United States, August–December 2014: Results of Nationwide Surveillance

Abstract

Background During late summer/fall 2014, pediatric cases of acute flaccid myelitis (AFM) occurred in the United States, coincident with a national outbreak of enterovirus D68 (EV-D68)–associated severe respiratory illness. Methods Clinicians and health departments reported standardized clinical, epidemiologic, and radiologic information on AFM cases to the Centers for Disease Control and Prevention (CDC), and submitted biological samples for testing. Cases were ≤21 years old, with acute onset of limb weakness 1 August–31 December 2014 and spinal magnetic resonance imaging (MRI) showing lesions predominantly restricted to gray matter. Results From August through December 2014, 120 AFM cases were reported from 34 states. Median age was 7.1 years (interquartile range, 4.8–12.1 years); 59% were male. Most experienced respiratory (81%) or febrile (64%) illness before limb weakness onset. MRI abnormalities were predominantly in the cervical spinal cord (103/118). All but 1 case was hospitalized; none died. Cerebrospinal fluid (CSF) pleocytosis (>5 white blood cells/μL) was common (81%). At CDC, 1 CSF specimen was positive for EV-D68 and Epstein-Barr virus by real-time polymerase chain reaction, although the specimen had >3000 red blood cells/μL. The most common virus detected in upper respiratory tract specimens was EV-D68 (from 20%, and 47% with specimen collected ≤7 days from respiratory illness/fever onset). Continued surveillance in 2015 identified 16 AFM cases reported from 13 states. Conclusions Epidemiologic data suggest this AFM cluster was likely associated with the large outbreak of EV-D68–associated respiratory illness, although direct laboratory evidence linking AFM with EV-D68 remains inconclusive. Continued surveillance will help define the incidence, epidemiology, and etiology of AFM.

Enterovirus D-68 Infection, Prophylaxis, and Vaccination in a Novel Permissive Animal Model, the Cotton Rat (Sigmodon hispidus)

“…Increasing numbers of EV-D68 cases showing acute flaccid paralysis and cranial nerve dysfunction in children raised concerns about its potential impact on public health [27–29, 41, 42]. However, the underlying causes for this upsurge of EV-D68 infections are still unknown.…”

Acute flaccid myelitis: A clinical review of US cases 2012–2015

“…Between August and December of 2014, 120 children from 34 US states met the criteria. 8 Ten children meeting the CDC AFM case definition and 1 additional child with cranial nerve dysfunction presenting to Primary Children’s Hospital (PCH) in Utah during the 2014 enterovirus D68 outbreak were subsequently reported. 10 Tables 1 and 2 summarize clinical characteristics of the CDPH, CHCO, and PCH cohorts of AFM described above, as well as nation-wide CDC epidemiological data.…”

Outbreaks of acute flaccid myelitis in the US

“…Enteroviruses A71 and D6878 have both been associated with acute flaccid myelitis, but D68 is emerging as the leading causal candidate. …”

“…At the same time, many cases of acute flaccid myelitis were reported among US children,8 some of whom had laboratory confirmed enterovirus D68 infection 811. Limb weakness or disability can persist for more than 18 months after infection among children with acute flaccid myelitis associated with enterovirus D68 712…”

“…Many scientists believe this regular cycling is due to the seroprevalance of enterovirus antibodies waning in the population every two years, as new children are born without immunity 15. Secondly, there is a temporal association between previous outbreaks of enterovirus D68 and acute flaccid myelitis,13 for example, in the US in 2014 8. Thirdly, enterovirus D68 infects human neurones—a recent study shows that enterovirus D68 strains, including 2014 strains, can enter and replicate in neuronal cells 16.…”