ARTICLE IN PRESS +Model An Pediatr (Barc). 2020;xxx(xx):xxx---xxx www.analesdepediatria.org SCIENTIFIC LETTER Clinical features and origin of cases of parotiditis in an emergency department  Caracterización clínica y etiológica de los casos de parotiditis en un servicio de urgencias To the editor: The mumps virus (MuV), or Myxovirus parotiditis, contin- ues to cause sporadic cases and outbreaks of disease. This is associated to the progressive waning of immunity against the mumps component of the measles, mumps, rubella (MMR) vaccine in absence of a natural booster (especially from 10 years after administration of the second dose), the use in the 1993---1999 period of a vaccine that had the Rubini strain, which proved to be less effective, and the presence of pock- ets of unvaccinated people in the population. 1 In Spain, 10 260 cases were notified in 2017 and 8996 in 2018, a signifi- cant increase compared to previous seasons. 2 Some of the infectious agents other than MuV that may be involved in parotitis as a general clinical presentation include influenza A virus, parainfluenza virus, Epstein-Barr virus (EBV), adenovirus, coxsackievirus, cytomegalovirus (CMV), parvovirus B19, herpesvirus and lymphocytic chori- omeningitis virus, as well as gram-positive bacteria, atypical mycobacteria and Bartonella species. 3---5 In the paediatric population, these pathogens are probably more frequent causative agents compared to MuV. This, combined with the benign course of most presentations, leads many paediatric health care facilities to make the diagnosis without an aeti- ological investigation. The aim of our study was to establish the viruses involved in cases of parotitis in our area. We carried out a retrospective study through the collec- tion of data corresponding to 2 full years (2016 and 2017), including all patients given a diagnosis of parotitis (with swelling of the parotid glands being a requirement for inclu- sion) in the paediatric emergency department of a tertiary  Please cite this article as: Scatti-Regàs A., Aguilar-Ferrer M.C., Antón-Pagarolas A., Martínez-Gómez X., González-Peris S. Carac- terización clínica y etiológica de los casos de parotiditis en un servicio de urgencias. An Pediatr (Barc). 2019. https://doi.org/10. 1016/j.anpedi.2019.11.004 care hospital in Barcelona that manages patients up to age 16 years and based on diagnostic judgment of the pae- diatrician in charge of the patient. Per hospital protocol, polymerase chain reaction (PCR) tests for detection of MuV in saliva and urine samples were performed in patients with parotitis. Serologic tests were added if blood tests were requested by the paediatrician in charge based on his or her clinical judgment. When it came to serologic testing, in case of negative results of the test for detection of MuV in saliva, molecular methods were used for detection of influenza A and B virus, respiratory syncytial virus A/B, ade- novirus, metapneumovirus, coronavirus nl63/OC43/229E, enterovirus, rhinovirus, parainfluenza virus, EBV and CMV. Mump viruses were characterised by partial sequencing of the small hydrophobic (SH) gene. We identified 169 cases of symptomatic acute parotitis (0.21% or paediatric emergency visits). The median age of the patients was 7.7 years (range, 11 months-16.8 years). The rate of adherence to the protocol for the ordering of tests for aetiological diagnosis was 79.3%, so we were able to obtain data on testing of saliva samples from 134 patients. Fig. 1 summarises the results of PCR testing of these sam- ples. Another 5 patients received an aetiological diagnosis of parotitis due to MuV by serologic testing (positive IgM test), adding up to a total of 18 cases caused by MuV. The median age of patients with MuV infection (in all cases MuV genotype G) was 14.3 years (range, 18 months- 16.8 years), with a predominance of the male sex (72.2%). In 3 cases (16.7%) there was no known history of contact with a case of parotitis. All patients were correctly vacci- nated save for 2 children that had not received any dose of MMR by parental choice and 1 adolescent that had only received 1 dose of vaccine. There were no documented complications, except for 1 patient that developed Guillain- Barré syndrome with onset the week after the initial visit, who had a favourable outcome. The management of 19.1% of the patients included empiric antibiotherapy despite there being no evidence confirming bacterial infection. Table 1 presents the demographic and clinical character- istics of cases of parotitis in which testing was performed for investigation of the aetiology. Patients with MuV infec- tion were significantly older compared to children with a different aetiological agent (median age, 14.3 vs 6.5 years; P = .005). The findings in our study, despite the limitations intrinsic to its retrospective design, were consistent with those of other authors, and showed that a significant proportion of 2341-2879/© 2019 Asociaci´ on Espa˜ nola de Pediatr´ ıa. Published by Elsevier Espa˜ na, S.L.U. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). ANPEDE-2744; No. of Pages 3