Observed peaks of acute flaccid myelitis (AFM) cases have occurred biennially since 2014 in the United States. We aimed to determine if AFM etiology differed between peak and nonpeak years, considering that clinical features of AFM differ by virus etiology. We compared clinical and laboratory characteristics of AFM cases that occurred during peak (2016 and 2018, n = 366) and nonpeak (2015 and 2017, n = 50) years. AFM patients in peak years were younger (5.2 years) than those in nonpeak years (8.3 years). A higher percentage of patients in peak years than nonpeak years had pleocytosis (86% vs. 60%), upper extremity involvement (33% vs. 16%), and an illness preceding limb weakness (90% vs. 62%) and were positive for enterovirus or rhinovirus RNA (38% vs. 16%). Enterovirus D68 infection was associated with AFM only in peak years. Our findings suggest AFM etiology differs between peak and nonpeak years.

中文翻译：

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2015-2018年美国急性弛缓性脊髓炎患者的特征。

自2014年以来，美国每两年发生一次急性弛缓性脊髓炎（AFM）病例的观察高峰。考虑到AFM的临床特征因病毒病因而异，我们旨在确定AFM病因在高峰和非高峰年之间是否存在差异。我们比较了在高峰（2016和2018，n = 366）和非高峰（2015和2017，n = 50）年发生的AFM病例的临床和实验室特征。高峰期的AFM患者比非高峰期（8.3岁）年轻（5.2岁）。与非高峰期相比，高峰期患者的百分比更高（86％vs. 60％），上肢受累（33％vs. 16％）以及肢体无力之前患病（90％vs. 62％），并且肠病毒或鼻病毒RNA阳性（38％比16％）。肠道病毒D68感染仅在高峰时期与AFM相关。