Britton PN, et al. – This study focused on seasonal influenza–associated neurological disease (IAND) in Australian children. Authors identified seasonal influenza as an important cause of acute neurological disease in these children. The spectrum of seasonal IAND appeared similar to that described during the 2009 H1N1 pandemic. Influenza–associated encephalitis/encephalopathy (IAE) appeared associated with high morbidity and mortality.

Methods

• Authors obtained prospectively acquired Australian surveillance data from 2 studies nested within the Paediatric Active Enhanced Disease Surveillance (PAEDS) network: the Influenza Complications Alert Network (FluCAN) study and the Australian Childhood Encephalitis (ACE) study between 2013 and 2015.
• The clinical features and severity of IAND in children, including influenza–associated encephalitis/encephalopathy (IAE) were described.
• The proportion of hospitalized influenza that was associated with IAND and IAE, and incidence of IAE was calculated.

Results

• Over 3 influenza seasons, 54 cases of IAND were identified at 2 tertiary children’s hospitals from Australia that accounted for 7.6% of hospitalized influenza.
• 10/54 cases were of IAE (1.4% hospitalized influenza).
• Among Australian children (aged ≤14 years), the mean annual incidence of IAE was 2.8 per 1000000.
• IAND was observed to had broad spectrum and this included IAE (n = 10) including distinct acute encephalopathy syndromes, simple febrile seizures (n = 14), other seizures (n = 16), acute ataxia (n = 4), and other subacute syndromes (transverse myelitis [n = 1], opsoclonus myoclonus [n = 1]).
• In this study, two–thirds of children with IAND were aged ≤4 years; less than half indicated preexisting neurological disease or other risk factors for severe influenza.
• In half of cases, IAE resulted in death or neurological morbidity.