The causes and clinical features of childhood encephalitis in Australia: A multicentre, prospective, cohort study

Abstract

Background. We aimed to determine the causes, clinical features and outcome of encephalitis in Australian children. Methods. We prospectively identified children aged 0 to ≤14 years with suspected encephalitis at five tertiary paediatric hospitals between May 2013 and December 2015 using the Paediatric Active Enhanced Disease Surveillance (PAEDS) network. A multidisciplinary expert panel reviewed cases and categorised them as encephalitis or not encephalitis using published definitions. Encephalitis cases were further categorised into the etiologic subgroups: infectious, immune-mediated or unknown. Results. To December, 2015, we identified 194 children with encephalitis (60% of total suspected cases): 59% (95% CI 52-66) had infectious causes, including 12% enterovirus, 11% human parechovirus, 6% herpes simplex virus, 6% influenza, 5% Mycoplasma pneumoniae and 5% bacterial meningo-encephalitis; 21% (95% CI 15-26) had immune mediated encephalitis, including 14% acute disseminated encephalomyeltis (ADEM) and 5% anti-NMDAR encephalitis; 20% (95% CI 14-25) had unknown causes. 56% of cases were male. Infectious encephalitis occurred in younger children (median age 1.7 years, IQR 0.1-6.6) than immune-mediated encephalitis (9.1 years, IQR 4.5-10.9). Unknown encephalitis showed a bimodal distribution with peaks <1 year and at 8 years of age. Nine patients died (case fatality proportion 5%), 7 with infectious causes (2 influenza-associated, 3 human herpes virus 6-associated, 1 parechovirus, 1 Group B streptococcus); and 2 with unknown causes. 24% (95% CI 18-31) of children showed moderate to severe neurological sequelae at discharge from hospital (Glasgow outcome scale score ≤4). Conclusion. The causes of childhood encephalitis differ from those in adults. Epidemic viral infections predominate, especially in the very young. The most common specified causes were ADEM, enteroviruses and parechovirus, and only one fifth of cases have unknown cause. Mortality is associated with an infectious cause; death or moderate neurological morbidity occurs in approximately a third of cases.L6278051752019-05-29 <br />