Genomic Analyses of Acute Flaccid Myelitis Cases among a Cluster in Arizona Provide Further Evidence of Enterovirus D68 Role.

Enteroviruses are a common cause of respiratory and gastrointestinal illness, and multiple subtypes, including poliovirus, can cause neurologic disease. In recent years, enterovirus D68 (EV-D68) has been associated with serious neurologic illnesses, including acute flaccid myelitis (AFM), frequently preceded by respiratory disease. A cluster of 11 suspect cases of pediatric AFM was identified in September 2016 in Phoenix, AZ. To determine if these cases were associated with EV-D68, we performed multiple genomic analyses of nasopharyngeal (NP) swabs and cerebrospinal fluid (CSF) material from the patients, including real-time PCR and amplicon sequencing targeting the EV-D68 VP1 gene and unbiased microbiome and metagenomic sequencing. Four of the 11 patients were classified as confirmed cases of AFM, and an additional case was classified as probable AFM. Real-time PCR and amplicon sequencing detected EV-D68 virus RNA in the three AFM patients from which NP swabs were collected, as well as in a fourth patient diagnosed with acute disseminated encephalomyelitis, a disease that commonly follows bacterial or viral infections, including enterovirus. No other obvious etiological causes for AFM were identified by 16S or RNA and DNA metagenomic sequencing in these cases, strengthening the likelihood that EV-D68 is an etiological factor. Herpes simplex viral DNA was detected in the CSF of the fourth case of AFM and in one additional suspect case from the cluster. Multiple genomic techniques, such as those described here, can be used to diagnose patients with suspected EV-D68 respiratory illness, to aid in AFM diagnosis, and for future EV-D68 surveillance and epidemiology.IMPORTANCE Enteroviruses frequently result in respiratory and gastrointestinal illness; however, multiple subtypes, including poliovirus, can cause severe neurologic disease. Recent biennial increases (i.e., 2014, 2016, and 2018) in cases of non-polio acute flaccid paralysis have led to speculations that other enteroviruses, specifically enterovirus D68 (EV-D68), are emerging to fill the niche that was left from poliovirus eradication. A cluster of 11 suspect cases of pediatric acute flaccid myelitis (AFM) was identified in 2016 in Phoenix, AZ. Multiple genomic analyses identified the presence of EV-D68 in the majority of clinical AFM cases. Beyond limited detection of herpesvirus, no other likely etiologies were found in the cluster. These findings strengthen the likelihood that EV-D68 is a cause of AFM and show that the rapid molecular assays developed for this study are useful for investigations of AFM and EV-D68.

Safety, tolerability, and efficacy of fluoxetine as an antiviral for acute flaccid myelitis.

OBJECTIVE: To determine the safety, tolerability, and efficacy of fluoxetine for proven or presumptive enterovirus (EV) D68-associated acute flaccid myelitis (AFM). METHODS: A multicenter cohort study of US patients with AFM in 2015-2016 compared serious adverse events (SAEs), adverse effects, and outcomes between fluoxetine-treated patients and untreated controls. Fluoxetine was administered at the discretion of treating providers with data gathered retrospectively. The primary outcome was change in summative limb strength score (SLSS; sum of Medical Research Council strength in all 4 limbs, ranging from 20 [normal strength] to 0 [complete quadriparesis]) between initial examination and latest follow-up, with increased SLSS reflecting improvement and decreased SLSS reflecting worsened strength. RESULTS: Fifty-six patients with AFM from 12 centers met study criteria. Among 30 patients exposed to fluoxetine, no SAEs were reported and adverse effect rates were similar to unexposed patients (47% vs 65%, p = 0.16). The 28 patients treated with >1 dose of fluoxetine were more likely to have EV-D68 identified (57.1% vs 14.3%, p < 0.001). Their SLSS was similar at initial examination (mean SLSS 12.9 vs 14.3, p = 0.31) but lower at nadir (mean SLSS 9.25 vs 12.82, p = 0.02) and latest follow-up (mean SLSS 12.5 vs 16.4, p = 0.005) compared with the 28 patients receiving 1 (n = 2) or no (n = 26) doses. In propensity-adjusted analysis, SLSS from initial examination to latest follow-up decreased by 0.2 (95% confidence interval [CI] -1.8 to +1.4) in fluoxetine-treated patients and increased by 2.5 (95% CI +0.7 to +4.4) in untreated patients (p = 0.015). CONCLUSION: Fluoxetine was well-tolerated. Fluoxetine was preferentially given to patients with AFM with EV-D68 identified and more severe paralysis at nadir, who ultimately had poorer long-term outcomes. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for patients with EV-D68-associated AFM, fluoxetine is well-tolerated and not associated with improved neurologic outcomes.