Characteristics of Patients with Acute Flaccid Myelitis, United States, 2015–2018

Abstract

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Enterovirus D68 molecular and cellular biology and pathogenesis

“…The median age at presentation reported in the United States and Europe from 2014 to 2018 ranged from 4.0 to 7.8 years. Though the age range of cases extends into young adulthood, the vast majority of cases have been in children younger than 10 years ( 192 , 198 ). EV-D68 infections are thought to be widespread, as suggested by a high rate of mild infections found on prospective surveillance ( 74 ).…”

Enterovirus D68–Associated Acute Flaccid Myelitis, United States, 2020

“…Yield of EV/RV and EV-D68 testing among AFM patients is dependent on timing and type of specimen collection and is higher among respiratory specimens collected within 5-7 days of respiratory or febrile illness onset (8,9). Of note, EV-D68 was not detected in specimens from any patients with onset during the nonpeak years of 2015 and 2017, suggesting that EV-D68 is playing a role in the increases in AFM cases every 2 years but plays less of a role during nonpeak years (17).…”

“…The clinical manifestations and epidemiology of confirmed AFM cases strongly suggests an infectious etiology, probably viral. Most AFM cases are in patients with prodromal symptoms consistent with a viral illness before onset of limb weakness, and AFM patients in peak years are significantly more likely to have prodromal respiratory illness or fever than those in nonpeak years (9,10,17). In addition, the increase in AFM noted in 2014 coincided with an unusual increase in severe respiratory illness caused by enterovirus D68 (EV-D68) in the United States; 11 (20%) of 56 AFM patients whose respiratory specimens were tested at CDC in 2014 were positive for EV-D68 (8,18).…”

“…Since 2014, enteroviruses and rhinoviruses (EV/RVs) have been the most common pathogens detected in clinical specimens from AFM patients, primarily among respiratory specimens, and EV-D68 is the single most common virus detected (8)(9)(10). In 2016 and 2018, 38% of all AFM patients with >1 clinical specimen tested at CDC were positive for EV/RV (17). EV-D68 was detected in 21%, enterovirus A71 (EV-A71) in 5%, and various other EV/ RV were detected in 12%.…”

“…Differentiating clinical case characteristics in peak AFM years compared with nonpeak years might provide clues about viral pathogenesis. For instance, AFM patients in peak years were more likely to have upper limb involvement compared with patients in nonpeak years (17). In contrast, a predominance of lower limb involvement is observed in patients with paralytic poliovirus infection (30).…”