Epidemiology of acute flaccid myelitis in children in the Netherlands, 2014 to 2019

Background: Acute flaccid myelitis (AFM) is a polio-like condition affecting mainly children and involving the central nervous system (CNS). AFM has been associated with different non-polio-enteroviruses (EVs), in particular EV- D68 and EV-A71. Reliable incidence rates in European countries are not available. Aim: To report AFM incidence in children in the Netherlands and its occurrence relative to EV-D68 and EV-A71 detections. Methods: In 10 Dutch hospitals, we reviewed electronic health records of patients diagnosed with a clinical syndrome including limb weakness and/or CNS infection and who were < 18 years old when symptoms started. After excluding those with a clear alternative diagnosis to AFM, those without weakness, and removing duplicate records, only patients diagnosed in January 2014- December 2019 were retained and further classified according to current diagnostic criteria. Incidence rates were based on definite and probable AFM cases. Cases' occurrences during the study period were co-examined with laboratory-surveillance detections of EV- D68 and EV-A71. Results: Among 143 patients included, eight were classified as definite and three as probable AFM. AFM mean incidence rate was 0.06/100,000 children/year (95% CI: -0.03 to 0.14). All patient samples were negative for EV-A71. Of respiratory samples in seven patients, five were EV- D68 positive. AFM cases clustered in periods with increased EV-D68 and EV-A71 detections. Conclusions: AFM is rare in children in the Netherlands. The temporal coincidence of EV- D68 circulation and AFM and the detection of this virus in several cases' samples support its association with AFM. Increased AFM awareness among clinicians, adequate diagnostics and case registration matter to monitor the incidence.