Seizures and Encephalitis in Children with Flu

Over 7% of children hospitalized for influenza in Australia have influenza-associated neurological disease, and children under age five are most at risk, according to results published online in ClinicalInfectious Diseases.

Not much information exists on neurological diseases associated with seasonal influenza in children.  The investigation is the first longitudinal study on the issue from the Southern Hemisphere, and few such studies have been done in the Northern Hemisphere.

“We have shown that seasonal influenza is an important cause of neurological disease in Australian children. At the most severe end, influenza associated encephalitis occurs in approximately one percent of influenza hospitalisations,” wrote first author Philip Britton, MBBS, FRACP, of The Children’s Hospital at Westmead (Westmead, NSW, Australia), and colleagues.

The wide range of neurological disorders associated with influenza most often occur in children, and include seizures, meningitis, transverse myelitis, acute disseminated encephalomyelitis, Guillain-Barre syndrome, and encephalopathy/encephalitis. However, very little epidemiological information exists about the issue. 

To fill in the gaps, researchers used surveillance data from Influenza Complications Alert Network (FluCAN) study, and the Australian Childhood Encephalitis (ACE) study. Both studies were part of the Pediatric Active Enhanced Disease Surveillance (PAEDS) network in Australia. Data came from the 2013-2015 Southern Hemisphere flu seasons (April to October).

Key Results for 2013-2015:

• Of 710 children hospitalized for influenza, 7.6% (54/710) had influenza-associated neurological disease:

♦ Two-thirds were ≤4 years

♦ Less than 50% had pre-existing neurological disease or other risk factors for severe influenza

• 1.4% (10/710) of children hospitalized with influenza-associated neurological disease had influenza-associated encephalitis/encephalopathy

♦ Two patients died, three developed continued neurological sequelae

• 55% (30/54) of children with influenza-associated neurological disease had acute seizure:

♦ 14 had simple febrile seizures, 3 had status epilepticus

• 80% (41/51) of surviving children completely recovered or regained pre-morbid functioning

• Most children who developed influenza-associated neurological disease did not receive influenza vaccination (only 2 received vaccinations)

The authors noted the high morbidity and mortality associated with influenza-associated encephalitis. They urged physicians to consider influenza as the underlying cause of encephalitis in children presenting during flu season.

“[L]ocal encephalitis guidelines should consider inclusion of empiric treatment with oseltamivir, whilst awaiting investigation results,” they wrote.

They also highlighted the strikingly low number of children who received influenza vaccinations, and suggested that many of these cases were preventable.

“[W]e have shown that influenza-associated neurological disease occurs primarily in children younger than five years and without pre-existing neurological disease or other risk factors for severe influenza. These findings support the case for universal influenza vaccination in young children,” they concluded.

Take-home Points

• The first study of its kind in Australia shows 7.6% of children hospitalized with influenza had influenza-associated neurological disease.

• 1.4% of children hospitalized with influenza had influenza-associated encephalitis.

• 55% of children with influenza-associated neurological disease had acute seizure.

• The authors urge universal influenza vaccination; they also suggested initial empiric treatment with oseltamivir in children presenting with encephalitis during flu season.

One or more authors reports grants and/or travel support from one or more of the following: GSK, Novartis, Pfizer and Seqiris, BioCSL/Seqiris, Sanofi, Novartis, and/or Medimmune/Astra Zeneca.

Reference: Britton PN, et al. The spectrum and burden of influenza-associated neurological disease in children: combined encephalitis and influenza sentinel site surveillance from Australia 2013-2015. Clin Infect Dis. 2017 Apr 29.