The epidemiology of aseptic meningitis in New Zealand children from 1991 to 2020

Aim Aseptic meningitis, including culture negative and viral meningitis, contributes a significant health-care burden, including unnecessary antibiotic use and hospitalisation to treat possible bacterial meningitis. This study analysed aseptic meningitis hospitalisations in New Zealand (NZ) children over 29 years. Methods In this population-based study, aseptic meningitis hospitalisations in NZ children <15 years old were analysed from 1991 to 2020. Incident rate ratios were calculated using Poisson regression models. Variations in hospitalisations by age, year, sex, ethnicity, geographical region and socio-economic deprivation were analysed. Results There were 5142 paediatric aseptic meningitis hospitalisations from 1991 to 2020. Most were unspecified viral meningitis (64%), followed by enterovirus (29%). Hospitalisation rates varied annually with a median of 18.4/100 000 children including a peak in 2001 of 56.4/100 000 (51.7-61.6). From 2002 to 2019, rates increased by 8.4%/year (7.2-9.5%) in infants <90 days old but decreased in all other age groups. In 2020, a reduction in hospitalisations to 9.6/100 000 (7.9-11.8) occurred, and in infants <90 days old were 0.37 times expected. Hospitalisations were 1.50 times (1.49-1.68) higher in males than females; higher in children of Maori (P < 0.001) and Pacific (P < 0.001) versus European ethnicity; and higher for children living in the most (2.44 times, (2.16-2.75)) versus least deprived households; and in northern versus southern NZ. Conclusions Aseptic meningitis hospitalisations increased in young infants during 29 years of surveillance, apart from 2020 when admissions reduced during the COVID-19 pandemic. In contrast, hospitalisations decreased in children aged >1 year. Further investigation into reasons for higher admissions by ethnic group, geographical location and increased deprivation are required.