Influenza can result in severe neurological complications. We sought to describe influenza associated neurological disease identified over two seasons by the Australian childhood encephalitis (ACE) study.
We undertook prospective hospital surveillance for suspected encephalitis (SE) using the paediatric active enhanced disease surveillance (PAEDS) network in NSW from May 2013 and nationally (NSW, QLD, SA, VIC, WA) from 2014. Cases were ascertained by screening hospital admissions for keywords. Demographic, clinical, exposure, diagnostic and outcome data were acquired. Cases with influenza confirmed by PCR on an acute specimen were classified three months post admission as confirmed encephalitis or ‘not encephalitis’.
We identified 14 cases of influenza associated neurological disease over two seasons: nine were male; median age was three years, and eight were admitted to ICU. Eight met the definition for confirmed infectious encephalitis, all of whom were < 5 years of age and mostly lacked CSF pleocytosis. Six did not meet the definition. None of the 12 children for whom data was available had received seasonal influenza immunisation. We identified four children with well-defined influenza clinico-radiological CNS syndromes: 1 ‘acute necrotising encephalopathy’ (ANE), 1 ‘mild encephalopathy with reversible splenial lesion’ (MERS), and 2 ‘acute encephalopathy with biphasic seizures and late reduced diffusion’ (AESD). One child died (ANE), and three had significant neurological sequelae at discharge. Influenza was associated with 10% of cases of childhood encephalitis cases in the ACE study (2013-2014).
Influenza is an uncommon but important cause of childhood encephalitis in Australia which can manifest as a wide clinical spectrum of clinico-radiological syndromes. It occurs mainly in young children and can result in mortality and severe morbidity.
R. Booy, None
C. Blyth, None
N. Crawford, None
H. Marshall, None
E. Elliott, None
C. Jones, None