Original Studies Enterovirus-A71 Rhombencephalitis Outbreak in Catalonia: Characteristics, Management and Outcome Núria Wörner, MD,* Rocío Rodrigo-García, MD,* Andrés Antón, MD, PhD,†‡§ Ester Castellarnau, MD,¶ Ignacio Delgado, MD,∥ Èlida Vazquez, MD, PhD,∥ Sebastià González, MD,* Lluís Mayol, MD,** Maria Méndez, MD,†† Eduard Solé, MD,‡‡ Jaume Rosal, MD,§§ Cristina Andrés,†‡ Alejandro Casquero, MD,* Esther Lera, MD,* Mónica Sancosmed, MD,* Magda Campins, MD, PhD,‡§¶¶ Tomàs Pumarola, MD, PhD,†‡§ and Carlos Rodrigo, MD, PhD*‡∥∥ review of clinical characteristics, diagnosis, treatment and outcome of these Background: Between April and June 2016, an outbreak of rhomben- patients was conducted. cephalitis (RE) caused by enterovirus (EV) A71 was detected in Catalonia, Results: Sixty-four patients met the clinical and virologic criteria for Spain—the first documented in Western Europe. The clinical characteristics rhombencephalitis caused by EV-A71. All patients had symptoms sug- and outcome of patients with this condition differed from those reported in gesting viral disease, mainly fever, lethargy, ataxia and tremor, with 30% outbreaks occurring in Southeast Asia. of hand-foot-mouth disease. Intravenous immunoglobulin therapy was Methods: Observational, multicenter study analyzing characteristics, treat- given to 44/64 (69%) patients and methylprednisolone to 27/64 (42%). ment and outcome of patients with EV-A71 rhombencephalitis diagnosed Six patients (9%) required pediatric intensive care unit admission. Three in 6 publicly funded hospitals within the Catalonian Health Institute. A patients had acute flaccid paralysis of 1 limb, and another had autonomic nervous system (ANS) dysfunction with cardiorespiratory arrest. Outcome in all patients (except the patient with hypoxic-ischemic encephalopathy) Accepted for publication January 27, 2021 From the *Pediatric Emergency Department, Department of Pediatrics, Vall was good, with complete resolution of the symptoms. d’Hebron University Hospital, Barcelona, Spain; †Department of Microbi- Conclusions: During the 2016 outbreak, rhombencephalitis without ANS ology, Vall d’Hebron University Hospital, Barcelona, Spain; ‡Vall d’Hebron symptoms was the predominant form of presentation and most patients Research Institute, Barcelona, Spain; §Universitat Autònoma de Barcelona, showed no hand-foot-mouth disease. These findings contrast with those Barcelona, Spain; ¶Department of Pediatrics, Joan XXIII University Hos- pital, Tarragona, Spain; ∥Department of Pediatric Radiology, Vall d’Hebron of other patient series reporting associated ANS dysfunction (10%–15%) University Hospital, Barcelona, Spain; **Department of Pediatrics, Josep and hand-foot-mouth disease (60%–80%). Complete recovery occurred in Trueta University Hospital, Girona, Spain; ††Department of Pediatrics, Ger- almost all cases. In light of the favorable outcome in untreated mild cases, mans Trias i Pujol University Hospital, Badalona, Spain; ‡‡Department of therapies for this condition should be reserved for patients with moderate- Pediatrics, Arnau de Vilanova University Hospital, Lleida, Spain; §§Depart- ment of Pediatrics, Verge de la Cinta Hospital, Tortosa, Spain; ¶¶Department severe infection. The main relevance of this study is to provide useful infor- of Preventive Medicine and Epidemiology, Vall d’Hebron University Hos- mation for setting priorities, management approaches and adequate use of pital, Barcelona, Spain; and ∥∥Faculty of Medicine at Germans Trias i Pujol resources in future EV-A71 associated rhombencephalitis outbreaks. University Hospital, Universitat Autònoma de Barcelona, Barcelona, Spain. Key Word: Enterovirus rhonbencephalitis Carlos Rodrigo, MD, PhD, is currently at the Department of Pediatrics, Ger- mans Trias i Pujol University Hospital, Badalona, Barcelona, Spain. (Pediatr Infect Dis J 2021;40:628–633) The authors have no conflicts of interest or funding to disclose. Ethical approval: Institutional Review Board approval (PR(AG) 373/2019) was obtained from the Vall d’Hebron University Hospital (HUVH) Clinical Research Ethics Committee. N.W. and R.R.-G. have contributed equally to this work. N.W. and R.R.-G. conceptualized and designed the study, drafted the initial article, and reviewed and revised the article. A.A. and C.A. did virologic E nteroviruses (EV) are a group of positive-sense, single-stranded RNA viruses lacking a lipid envelope. They belong to the genus Enterovirus within the Picornaviridae family and are classified into studies, analysis and interpretation of microbiologic data. They wrote the 4 species (EV-A to EV-D) according to their genotypic and pheno- virologic part of the article. T.P. did interpretation and of microbiologic data, typic characteristics. EV-A71, a well-recognized human pathogen, study supervision. I.D. and E.V. did IMR acquisition, analysis and interpreta- tion. They wrote the radiologic part of the article. E.C., S.G., L.M., M.M., has been divided into several genogroups (A to F) as well as subge- E.S., J.R., A.C., E.L. and M.S. did acquisition, analysis and interpretation of nogroups (in Europe, mainly C1 and C2 are found).1,2 clinical data. They collected the clinical data and described the major clinical Although EV-A71 infection is usually asymptomatic, this findings of the article. M.C. did statistical analysis, analysis and interpreta- virus is a known etiologic agent of hand, foot and mouth disease tion of epidemiologic data. She wrote the epidemiologic part of the article. C.R. did concept and design of the study, study supervisión and review of the (HFMD) epidemics, with neurologic involvement in a small per- article. He had full access to all the data in the study and takes responsibility centage of cases, including aseptic meningitis, rhombencephalitis for the integrity of the data and the accuracy of the data analysis. All authors (RE), acute flaccid paralysis (AFP) and neurogenic pulmonary did critical revision of the manuscript for important intellectual content. All edema (mainly in children younger than 5 years).1,3–5 The largest authors approved the final manuscript as submitted and agree to be account- able for all aspects of the work. outbreaks have been described in Asia and the Pacific area (Aus- tralia, China and Taiwan), where a surveillance program has been Address for correspondence: Carlos Rodrigo, MD, PhD, Department of Pediatrics, Germans Trias i Pujol University Hospital, Carretera de Canyet, s/n. 08916 set up, coordinated by the World Health Organization (WHO).1,4 Badalona, Barcelona, Spain. E-mail: crodrigo.germasntrias@gencat.cat. In the northern hemisphere, EV circulation follows a seasonal Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. This pattern, with the highest incidence in summer and autumn, whereas is an open-access article distributed under the terms of the Creative Com- in tropical regions, no clear seasonal trends are evident. Since 2000, mons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC- sporadic cases of EV-A71 infection with neurologic involvement ND), where it is permissible to download and share the work provided it is other than aseptic meningitis have been documented in the United properly cited. The work cannot be changed in any way or used commercially without permission from the journal.2021 Kingdom, The Netherlands, Germany, Denmark and France.6 ISSN: 0891-3668/21/4007-0628 Between April and July in 2016, several cases of EV infec- DOI: 10.1097/INF.0000000000003114 tion with unusual clinical characteristics were detected in Catalonia 628 | www.pidj.com The Pediatric Infectious Disease Journal • Volume 40, Number 7, July 2021 Copyright © 2021 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. The Pediatric Infectious Disease Journal • Volume 40, Number 7, July 2021 Enterovirus-A71 Rombencephalitis Outbreak (Spain). A large number of patients showed neurologic symptoms method, as implemented in MEGA v5.2, with the evolutionary of severity, including AFP, RE with cranial nerve involvement and model with the lowest Bayesian information criterion score.8 Topo- bulbar symptoms (eg, dysarthria and difficulty swallowing), as well logic accuracy of the internal branch was evaluated using the boot- as other less severe manifestations, such as lethargy, tremor and strap method (1000 replicates). ataxia. As there was a progressive increase in these cases in the first Emergent MRI of the head and spine was performed in all few weeks, the Catalan health authorities decided to establish con- patients with AFP and moderate/severe forms of RE (according to sensus guidelines for the care of these patients, to unify the diagno- the consensus protocol), whereas MRI was carried out at the dis- sis and therapeutic management. cretion of the attending physician in patients with mild RE. The The aim of this study is to summarize the clinical and head imaging protocol included axial T1, T2, FLAIR and diffusion virologic characteristics of EV-A71-associated neurologic dis- sequences, as well as coronal FLAIR sequences with an optional ease in patients admitted to the pediatric departments of hos- postcontrast T1 sequence, followed by sagittal T2 sequences with pitals within the Catalan Health Institute (ICS, Institut Català an optional diffusion study of the entire spinal cord. A follow-up de la Salut) between April and July 2016, as well as to describe MRI (1–3 months after discharge, based on clinical criteria) was the diagnostic and therapeutic strategies implemented in these carried out only in patients whose first MRI study showed signifi- patients. cant abnormal findings and was limited to the affected anatomical region. In cases of acute moderate/severe neurologic dysfunction MATERIALS AND METHODS and high suspicion of EV infection, hospital admittance was indi- This is a prospective, observational, multicenter study cated for observation. Patients were monitored for signs of bul- focusing on the clinical characteristics, virologic features, treat- bar motor neuron involvement (dysarthria, dysphagia, drooling, ment and outcome of all cases of AFP and RE (with or without absent gag reflex, apneas, or respiratory abnormalities), spinal cord myelitis) in patients admitted to the pediatric departments of the 6 involvement (paresis or flaccid paralysis), myocardial involvement, ICS pediatric hospitals (Vall d’Hebron in Barcelona, Joan XXIII in neurogenic pulmonary edema, lethargy, or convulsions. Tarragona, Germans Trias i Pujol in Badalona, Doctor Josep Trueta The treatment protocol according to the patients’ clinical in Girona, Arnau de Vilanova in Lleida and Verge de la Cinta in involvement is shown in Table 2. Tortosa) during the outbreak of acute neurologic disease occurring The study was approved by the Vall d’Hebron Hospital between April and July 2016. Research Ethics Committee. The definitions of RE case used in the study are shown in Table 1. Detection of EV and other respiratory viruses in nasopharyn- RESULTS geal aspirates was carried out using a real-time multiplex RT-PCR From April to July 2016, 123 patients meeting the defini- assay (Allplex Respiratory Panel Assay, Seegene, Korea). EV detec- tion of a clinically suspected case were hospitalized. EV-A71 was tion in pharyngeal swabs, whole blood, stool samples and cerebro- detected in at least one of the tested samples from 64/123 (52%) spinal fluid (CSF) was performed with an EV-specific real-time RT- patients of which 54/64 were confirmed cases and 10/64 were PCR (RealCycler Enterovirus+Parechovirus kit, Progenie Molecular, clinical cases (see Table 1 for definitions). In the remaining 59/123 Spain). In addition, the GeneXpert EV test (Cepheid, United States) (48%) patients, other EVs (1 EV-E30 and 3 EV-C109) were found, was performed in some cases for rapid EV detection in CSF or naso- or no virus was detected. Based on phylogenetic analysis of partial pharyngeal aspirates, following manufacturer’s protocol with minor VP1 sequences from detected EV-A71 viruses, 61/64 (95%) strains modifications. Before PCR-based assays, total nucleic acids were belonged to subgenogroup C1, whereas the remaining 3/64 (5%) extracted using NucliSense easyMAG (bioMérieux, Marcy l’Etoile, did to subgenogroup C2. France) according to the manufacturer’s instructions, and kept frozen Mean age of cases was 21 months (IQR 12–39 months) and (−20°C) until use. In addition, a complete blood count and general 58% (37/64) were males. Before hospital admission, all patients biochemistry tests were performed in all patients. had experienced signs and symptoms suggesting a viral infection Phylogenetic analysis of the partial VP1 coding-region for a mean of 3 days (range 0–9 days). Fever, lethargy, ataxia and sequence of the detected EV was carried out for molecular charac- tremor predominated among the symptoms recorded in the emer- terization. Partial VP1 amplification and sequencing were based on gency room (Fig. 1). The findings from complementary examina- the protocol recommended by the WHO,7 with minor modifications. tions are summarized in Table 3. Nucleotide sequences were edited and assembled using MEGA Cranial computed tomography was performed in 5 patients, v5.2,8 together with reference sequences of EV types belonging to with normal findings in each test. Although this imaging technique the 4 species (EV-A to EV-D) downloaded from NCBI GenBank. can be useful to rule out other conditions, it is not very useful for Before phylogenetic analysis, the molecular evolutionary models of identifying EV-A71 related hindbrain lesions.3 Imaging test of nucleotide substitutions were fitted to the multiple sequence align- choice is head and spine MRI, which shows hyperintensities on T2 ments using evolutionary analysis, conducted in MEGA v5.2.8 Phy- and FLAIR imaging and hypointensities on T1, with or without dif- logenetic trees were constructed using a neighbor-joining distance fusion restriction in the dorsal part of the hindbrain, the dentate TABLE 1. Definitions of Rhombencephalitis Case Clinical Manifestation Laboratory Confirmation MRI Clinically suspected case Tremor, myoclonus, lethargy, bulbar symptoms and myelitis with no other known cause Clinical case Tremor, myoclonus, lethargy, bulbar symptoms and myelitis with no EV-A71 laboratory confirmation other known cause Confirmed case Tremor, myoclonus, lethargy, bulbar symptoms and myelitis with no EV-A71 laboratory confirmation Abnormalities other known cause © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. www.pidj.com | 629 Copyright © 2021 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. Wörner et al The Pediatric Infectious Disease Journal • Volume 40, Number 7, July 2021 TABLE 2. Treatment Indication According to the Patient’s Clinical Signs and Symptoms Clinical Severity Signs and Symptoms Treatment Mild Tremor No treatment Myoclonus Mild lethargy Mild ataxia Moderate Significant lethargy IVIg: 1 g/kg/24 h during 2 d Incipient bulbar symptoms Severe Established bulbar symptoms IVIg: 1 g/kg/24 h during 2 d Spinal cord symptoms (paresis or flaccid Consider: IV methylprednisolone 30 mg/ paralysis) kg/24 h (maximum dose, 1 g) during 3 d MR showing pattern of restricted diffusion nuclei of the cerebellum and the ventral portion of the spinal cord4 DISCUSSION (Fig. 2). EV infection is common in children younger than 5 years Intravenous immunoglobulins (IVIg) were given to 44/64 and usually manifests in mild clinical forms, such as HFMD or (69%) patients and methylprednisolone to 27/64 (42%), as soon as herpangina. Less commonly, causes aseptic meningitis. The out- the indication was determined according to Table 2, with no signifi- break described here is the most important documented in Western cant adverse effects. Six patients (9%) were admitted to the pediat- Europe up to 2016 regarding the number of cases compared with ric intensive care unit (PICU), and 5 required respiratory support another published series, mainly occurred in Southeast Asia and (2 of them needed invasive mechanical ventilation, 2 noninvasive Australia.1,4 In response to this situation, consensus guidelines for mechanical ventilation and 1 high-flow nasal cannulas). Three of the clinical diagnosis and management of this condition were elab- these 5 patients had AFP of 1 limb, and another showed autonomic orated and adapted according to the accumulated experience during dysfunction with acute neurogenic, noncardiogenic pulmonary the outbreak. For example, the indication for emergent MRI and the edema. While in the PICU, this last patient experienced cardiores- type of treatment were modified along with the outbreak duration. piratory arrest, with severe neurologic sequelae (hypoxic-ischemic There is a published paper about the same outbreak9 describing encephalopathy). The patient who did not require respiratory sup- cases of EV neurologic infections (none of them included in our port was admitted to the PICU for suspected myocardial dysfunc- study), but our series is exclusively focused on clinical, virologic tion, which was not confirmed later. and radiologic confirmed RE. Median duration of hospitalization was 5 days (range The age and symptoms prompting hospitalization in the 64 1–159) and duration of PICU admission was 5 days (IQR 4–7 children with EV-A71-associated RE in our series were similar to days). At the time of hospital discharge, 24/64 patients (38%) still those described in previous studies.3,4,10–13 All patients experienced showed mild neurologic symptoms: most had ataxia, and 2 patients a previous period consistent in viral disease. Ataxia and lethargy had weakness of 1 limb. The final outcome of these patients was are warning signs in the first stages of RE.3,12,14 It is likely that good, with complete resolution of the symptoms 6 months after dis- myoclonus during sleep in the first phases of the condition (32.8%, charge from hospital, except for the patient with hypoxic-ischemic Fig. 1) may have been underestimated in our series, as this variable encephalopathy. was not initially included in the clinical data collection. FIGURE 1. Most frequent signs and symptoms at hospital admission in patients with EV-A71S rhombencephalitis. 630 | www.pidj.com © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. Copyright © 2021 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. The Pediatric Infectious Disease Journal • Volume 40, Number 7, July 2021 Enterovirus-A71 Rombencephalitis Outbreak microbiologic diagnosis based on results from these samples.18 TABLE 3. Findings from Complementary Examinations Because of this, EV-A71 could not be confirmed as the causal in Patients With a Microbiologic Diagnosis of EV-A71 agent, although it is possible to establish an association between Infection this virus and the neurologic involvement. Our laboratory findings (Table 3) are in accordance with those described in the literature to Number date.3,4,10,11 of Cases Cranial computed tomography was performed in 5 patients, Blood analysis 48/49* Mean with normal findings in each test. Although this imaging technique Leukocytes 12,000 leukocytes/μL can be useful to rule out other conditions, it is not very useful for Neutrophils 6700 neutrophils/μL identifying EV-A71 related hindbrain lesions.3 Imaging test of C-reactive protein 0.9 mg/dL Procalcitonin 0.4 ng/mL choice is head and spine MRI, which shows hyperintensities on T2 Lumbar puncture 40/49* Mean: and FLAIR imaging and hypointensities on T1, with or without dif- Leukocytes 145 leukocytes/μL fusion restriction in the dorsal part of the hindbrain, the dentate Lymphocytes 80% nuclei of the cerebellum and the ventral portion of the spinal cord4 Proteins 40 mg/dL (Fig. 2). Glucose 64 mg/dL Hindbrain involvement on MRI was subtle in many patients, Bacterial culture 100% negative Bacterial PCR 100% negative and spinal cord involvement, although it was very evident, does Viral PCR 2 positives cases: EV-A71 not indicate the same degree of clinical severity in these patients and HHV6 as in myelitis caused by poliovirus or EV-D68. At the beginning EV isolated 64/64 of the outbreak, a patient was attended for tetraplegia caused by NPA 86% (55/64) EV-D68,19 and her MRI findings of RE and myelitis were compa- Stools 89% (57/64) Viral coinfections 15/49* rable with those of the EV-A71 infected patients with mild paresis Rhinovirus 60% and a favorable outcome. At the start of the outbreak and before the Adenovirus 26% causal agent had been identified, a larger number of neuroimaging Bocavirus 7% tests were performed and treatment was more aggressive. When it Rotavirus 7% was confirmed that these were diseases caused by different etiologic Brain and spinal cord MRI 60/64 agents, the diagnostic and therapeutic approaches were adapted to No evident abnormalities 9.3% (6/64) Sign of rhombencephalitis† 84.4% (54/64) the new data. Signs of myelitis 67.2% (43/64) The 5 patients in our series showing a restrictive diffu- Restricted diffusion 5/60 8.3% sion pattern on MRI (an indication of neuronal cytotoxic edema) *Data are available only for the 49 patients hospitalized in Hospital Universitario required PICU admission; hence, this finding could be a marker Vall d’Hebron of a poor clinical course. In the 2013 study of patients with acute †Signs of rhombencephalitis: T2 and FLAIR hyperintense lesions in the brainstem EV-A71 neurologic disease in Australia, all those with pulmonary particularly in pontine tegmentum (posterior aspect of the pons) or medulla, and or edema showed hindbrain diffusion restriction, suggesting acute dentate nuclei area. Signs of myelitis: Lineal hyperintensity within the upper aspect cervical cord with prediction to the anterior horns. Restricted diffusion: Additional cytotoxic damage.10 The clinical course of our RE patients clearly restricted diffusion (B:1000 hyperintensity, low ADC values) within focal T2 lesions at differed from that seen in EV-related sepsis or myocarditis. The EV the posterior aspect of the pons or medulla (poor prognosis). strains implicated in these infections and the clinical course were EV indicates enterovirus; MRI, magnetic resonance imaging; NPA, nasopharyngeal completely different. The neurogenic pulmonary edema caused by aspirate; HHV6, Human herpesvirus 6. severe autonomic dysfunction occurring in some patients should not be confused with heart failure associated with myocarditis, as In patients with an initial suspicion who were included in the this would have clinical and therapeutic repercussions. study, the most common detected EV was A71. Phylogenetic analy- IVIg treatment has been used since 200020 in countries sis showed that most of these viruses belonged to subgenogroup with EV-A71-related outbreaks of neurologic disease,11 based C1, and the percentage of C2 was very small, as reported in other on 2 premises: first, that the antibodies in immunoglobulins help European countries in 2016,15,16 and in previous years.15,17 But, in to neutralize the virus, and second, that the autonomic nervous addition to EV-A71, other nonpolio EV were also characterized in system (ANS) dysregulation and pulmonary edema or bleeding several specimens from clinical neurologic cases, as well as no EVs associated with EV-A71 disease are related to production of pro- were detected in some cases. Other nonpolio EV viruses can also inflammatory cytokines (interleukin [IL]-6, IL-10 and IL-3) and cause severe neurologic infections, although many cases may go chemokines (IL-8, IP-10, MCP-1 and possibly Mig).21–23 A ret- undiagnosed because EV typing data are not currently performed in rospective case study in Taiwan (China) suggested that IVIg can most European laboratories.18 This outbreak highlighted the lack of have an immunomodulatory effect in children with RE and ANS information regarding nonpolio EV circulating in the community dysregulation.24 despite the theoretical neurotropism of all EVs. It supports the idea Corticosteroids have also been used since 2000 in some series,10 that virologic surveillance should be strengthened in cases related analogous to the treatment of acute transverse myelitis (an immune- to mild disease as well as neurologic disease. mediated demyelinizing disease),25 although evidence of its true useful- The clinical and analytic features of EV-related RE differ ness for treating acute flaccid myelitis is lacking. The reason why we from those of EV meningitis. One significant difference is that EV used so many corticosteroids at the beginning of the outbreak was that detection in CSF is the rule in meningitis, but rare in RE, even in in February 2016 (2 months before the onset of the EV-A71 rhomben- cases with CSF pleocytosis. In fact, it is likely that in the few cases cephalitis outbreak), a patient with AFP caused by EV-D68 was admit- when EV is identified in CSF, patients first had meningitis clinical ted to the hospital, which progressed to tetraplegia. For this reason, and features and later RE, as other ones first had HFMD or herpangina. given the initial doubt that the new cases of neurologic involvement In RE or myelitis with AFP caused by EV, the virus is not expected caused by enterovirus could be due to EV-D68, treatment with corticos- to be present in CSF,18 but instead in respiratory (nasopharyngeal teroids was administered to the first patients of the outbreak although aspirate, nasopharyngeal smear or pharyngo-tonsillar smear) or the cases were not severe. In 2014, the Center for Disease Control and stool specimens, and it is currently recommended to establish the Prevention (CDC) concluded that corticosteroids are not indicated for © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. www.pidj.com | 631 Copyright © 2021 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. Wörner et al The Pediatric Infectious Disease Journal • Volume 40, Number 7, July 2021 FIGURE 2. A, hyperintensity on T2 and (B) hypointensity on T1-weighted images in the dorsal hindbrain region. C, Image of restricted diffusion (B1000 hyperintensity, ADC low values) in the dorsal aspect of the medulla caused by cytotoxic edema. D, Lineal hyperintensity within the upper anterior aspect of cervical cord. the treatment of AFP and that they carry a risk of worsening progno- outbreaks. We also found that severe forms were already severe at sis because of the immunosuppression. Nonetheless, judicious use the start of the manifestations of hindbrain involvement. Therefore, of corticosteroids could be helpful for managing severe spinal cord when EV infection was clinically suspected, we were able to recom- edema, which can worsen cord lesions. Hence, the potential benefits of mend strict monitoring during the first 24 hours, with lowering of these drugs for cord edema should be evaluated on an individual basis the alert level when clinical symptoms of bulbar involvement did because of the risk of worsening the viral infection caused by immuno- not develop. This led to a reduction in hospital monitoring, IVIg suppression.26 and corticosteroid treatment, and imaging tests. The outbreak had In our patients, the initial approach followed the reported a very acute beginning and end, so we were only able to adjust our recommendations we considered the most rigorous, and we estab- approach in a small number of patients, but we believe that our lished a diagnostic and treatment protocol for a potentially severe experience may be of value for similar outbreaks in the future. clinical situation. Because of the effective collaboration of all the The outcome was favorable in all our patients with the ICS pediatric hospitals and by daily review of the situation, we exception of one who had hypoxic-ischemic sequelae. There were noticed that not all the information in the literature was applica- no deaths. In contrast to other studies reporting ANS dysfunc- ble to our cases and that we could adapt our approach based on tion causing cardiac rhythm changes, myocarditis and pulmonary our direct data. Thus, we learned that HFMD, herpangina and other edema in 7%–14% of patients,10,12 only this single patient (2%) had signs and symptoms were not as frequent as they were in other ANS dysfunction. 632 | www.pidj.com © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. Copyright © 2021 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. The Pediatric Infectious Disease Journal • Volume 40, Number 7, July 2021 Enterovirus-A71 Rombencephalitis Outbreak Our series of EV-A71-related RE cases, collected using well- 8. Tamura K, Peterson D, Peterson N, et al. MEGA5: molecular evolution- defined criteria within the protocol developed, indicates that this con- ary genetics analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods. Mol Biol Evol. 2011;28:2731–2739. dition could be a different entity and not a complication of HFMD, 9. Casas-Alba D, de Sevilla MF, Valero-Rello A, et al. Outbreak of brainstem as had been considered in Asian outbreaks and in some reports that encephalitis associated with enterovirus-A71 in Catalonia, Spain (2016): a follow the WHO criteria and recommendations. The clinical course clinical observational study in a children’s reference centre in Catalonia. may differ from RE caused by an immune response or by other Clin Microbiol Infect. 2017;23:874–881. host genetic factors against infection caused by certain EVs, which 10. Teoh HL, Mohammad SS, Britton PN, et al. Clinical characteristics and remarks the need for the genetic characterization of all EVs detected functional motor outcomes of enterovirus 71 neurological disease in chil- in the laboratory, especially those associated with severe diseases. dren. JAMA Neurol. 2016;73:300–307. The increasing virulence and geographic spread of EV-A71 11. Cardosa J, Farrar J, Yeng C. A Guide to Clinical Management and Public Health Response for Hand, Foot and Mouth Disease (HFMD). World Health reported in last years has highlighted the need for a safe and effective Organization; 2011:1–71. vaccine to protect against the various genogroups and subgenogroups 12. Huang CC, Liu CC, Chang YC, et al. Neurologic complications in children of EV-A71.27 The developed vaccines have shown cross-protection with enterovirus 71 infection. N Engl J Med. 1999;341:936–942. against some EV-A71 genogroups and subgenogroups, but their pro- 13. Yang SD, Li PQ, Li YM, et al. Clinical manifestations of severe enterovirus tection is not complete and they do not protect against other EV spe- 71 infection and early assessment in a Southern China population. BMC cies; hence, their use is limited to controlling EV-A71 outbreaks.28,29 Infect Dis. 2017;17:153. In the absence of available vaccines, prevention and control 14. Lu HK, Lin TY, Hsia SH, et al. Prognostic implications of myoclonic measures are aimed at interrupting the chain of transmission. Fast jerk in children with enterovirus infection. J Microbiol Immunol Infect. detection of outbreaks and implementation of hygiene measures are 2004;37:82–87. the fundamental pillars to reduce serious forms of the disease. The 15. Midgley SE, Nielsen AG, Trebbien R, et al. Co-circulation of multiple sub- types of enterovirus A71 (EV- A71) genotype C, including novel recom- virus can be detected in oropharyngeal specimens 2 weeks after the binants characterised by use of whole genome sequencing (WGS), Denmark onset of the disease, and viral excretion in stool specimens lasts 2016. Euro Surveill. 2017;22:30565. during 4–8 weeks. Therefore, proper hand hygiene is essential to 16. Antona D, Kossorotoff M, Schuffenecker I, et al. Severe paediatric condi- interrupt transmission during outbreaks and should be stressed dur- tions linked with EV-A71 and EV-D68, France, May to October 2016. Euro ing the entire period that EV-A71 is excreted in stool (up to 11 Surveill. 2016;21:30402. weeks). Transmission by saliva or airborne respiratory droplets, 17. Karrasch M, Fischer E, Scholten M, et al. A severe pediatric infection with a however, cannot be ignored during the acute phase of the infection, novel enterovirus A71 strain, Thuringia, Germany. J Clin Virol. 2016;84:90–95. when EV-A71 is present in oropharyngeal specimens.3,30 18. Harvala H, Broberg E, Benschop K, et al. Recommendations for enterovirus diagnostics and characterisation within and beyond Europe. J Clin Virol. 2018;101:11–17. CONCLUSIONS 19. Cabrerizo M, García-Iñiguez JP, Munell F, et al. First cases of severe flaccid The EV-A71-associated RE outbreak that occurred in 2016 paralysis associated with enterovirus D68 infection in Spain, 2015-2016. in Catalonia was the first one with the described characteristics in Pediatr Infect Dis J. 2017;36:1214–1216. the European continent. The predominant clinical manifestation was 20. Li X, Mao C, Ma S, et al. Generation of neutralizing monoclonal antibod- RE. The outcome of the infection was favorable overall, with com- ies against enterovirus 71 using synthetic peptides. Biochem Biophys Res Commun. 2009;390:1126–1128. plete neurologic recovery in all patients except one, who experienced 21. Wang SM, Lei HY, Yu CK, et al. Acute chemokine response in the blood sequelae of hypoxic-ischemic encephalopathy following cardiorespi- and cerebrospinal fluid of children with enterovirus 71-associated brainstem ratory arrest of neurogenic origin. As most patients progressed well, encephalitis. J Infect Dis. 2008;198:1002–1006. we believe that treatments should be reserved for patients with mod- 22. Wang SM, Lei HY, Huang KJ, et al. Pathogenesis of enterovirus 71 erate-severe neurologic involvement. The main value of this article brainstem encephalitis in pediatric patients: roles of cytokines and cel- is to transmit information that we lacked at the start of the outbreak, lular immune activation in patients with pulmonary edema. J Infect Dis. which would have been useful to establish priorities, management 2003;188:564–570. criteria and proper use of resources for this infection. 23. Wang LC, Yao HW, Chang CF, et al. Suppression of interleukin-6 increases enterovirus A71 lethality in mice. J Biomed Sci. 2017;24:94. REFERENCES 24. Wang SM, Lei HY, Huang MC, et al. Modulation of cytokine production by intravenous immunoglobulin in patients with enterovirus 71-associated 1. Kok CC. Therapeutic and prevention strategies against human enterovirus brainstem encephalitis. J Clin Virol. 2006;37:47–52. 71 infection. World J Virol. 2015;4:78–95. 25. Defresne P, Meyer L, Tardieu M, et al. Efficacy of high dose steroid ther- 2. Lugo D, Krogstad P. Enteroviruses in the early 21st century: new manifesta- apy in children with severe acute transverse myelitis. J Neurol Neurosurg tions and challenges. Curr Opin Pediatr. 2016;28:107–113. Psychiatry. 2001;71:272–274. 3. Ooi MH, Wong SC, Lewthwaite P, et al. Clinical features, diagnosis, and 26. NCIRD C. Acute Flaccid Myelitis: Interim Considerations for Clinical management of enterovirus 71. Lancet Neurol. 2010;9:1097–1105. Management. Available at: httpwwwcdcgovacute-flaccid-myelitisdown- 4. Lee KY, Lee MS, Kim DB. Neurologic manifestations of enterovirus 71 loadsacute-flaccid-myelitispdf. 2014 Nov 7;1–11. Accessed April 22, infection in Korea. J Korean Med Sci. 2016;31:561–567. 2020. 5. Long L, Xu L, Xiao Z, et al. Neurological complications and risk factors of 27. Lee MS, Tseng FC, Wang JR, et al. Challenges to licensure of enterovirus 71 cardiopulmonary failure of EV-A71-related hand, foot and mouth disease. vaccines. PLoS Negl Trop Dis. 2012;6:e1737. Sci Rep. 2016;6:23444. 28. Yi EJ, Shin YJ, Kim JH, et al. Enterovirus 71 infection and vaccines. Clin 6. European Centre for Disease Prevention and Control. Outbreak of Exp Vaccine Res. 2017;6:4–14. Enterovirus A71 with Severe Neurological Symptoms Among Children in 29. Reed Z, Cardosa MJ. Status of research and development of vaccines for Catalonia, Spain 14 June 2016. ECDC; 2016:1–10. enterovirus 71. Vaccine. 2016;34:2967–2970. 7. World Health Organization Regional Office for Europe. Enterovirus 30. Chung PW, Huang YC, Chang LY, et al. Duration of enterovirus shedding in Surveillance Guidelines. World Health Organization; 2015:1–29. stool. J Microbiol Immunol Infect. 2001;34:167–170. © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. www.pidj.com | 633 Copyright © 2021 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.