Trends in Paediatric Viral Meningitis and Encephalitis With Unconfirmed Aetiology: A Spanish Population-Based Study, 2016-2020.

AIM: The prevalence of meningitis and encephalitis of unknown aetiology in Spanish children has not been specifically documented before. The aim of this study is to describe the epidemiology and trends of these clinical conditions between 2016 and 2020.

METHODS

Retrospective study analysing hospitalised children < 15 years with meningitis and encephalitis/encephalomyelitis of unknown origin (ICD-10 codes) in Spain (2016-2020). Data from National Registry of Hospitalizations and National Institute for Statistics were used to calculate age-stratified hospitalisation rates (HR). Statistical analysis included Poisson regression to calculate hospitalisation rate ratios (HRR) by age groups and years and forecasting methods to predict 2020 HRs.

RESULTS

Four thousand six hundred childrens were hospitalised with viral meningitis and encephalitis-encephalomyelitis of unknown origin, resulting in a HR of 7.8/105 inhabitants. The highest HR was observed in children under 1 year (49.1/105) and those aged 5-9 (10.4/105). The global HR for viral meningitis (3.64/105) was lower than for encephalitis-encephalomyelitis (4.2/105). Hospitalisations decreased from 1475 (2016) to 452 (2020), attributed to enhanced pathogen detection methods and COVID-19 preventive measures.

CONCLUSION

Undiagnosed central nervous system entities remain a significant cause of paediatric hospitalisations in Spain, despite a declining incidence. Enhanced diagnostic strategies, including expanded microbiological testing and molecular epidemiology surveillance, could prove beneficial.