Researchers from the Centers for Disease Control and Prevention (CDC) recently reported that 13% of U.S. children who died from the flu this season had influenza-associated encephalopathy or encephalitis (IAE). Among them, 4 had acute necrotizing encephalopathy (ANE), the most severe form, which can cause brain dysfunction and inflammation. As of February 8, CDC confirmed 68 pediatric flu deaths, including 9 with IAE. More than half of the children with fatal IAE had no underlying medical conditions. Only 20% of those with IAE had been vaccinated at least 2 weeks before becoming ill. CDC warns that clinicians should consider IAE in children with influenza and abnormal neurologic signs or symptoms. No national IAE surveillance exists, therefore, it’s hard to say whether this year’s cases are above and beyond what might be expected in a particularly active flu season. A more recent flu update on February 15 shows the number of pediatric deaths attributed to influenza now totals 86—although no additional data is available on how many of those may also be associated with IAE.
Diagnosing ANE: The diagnosis of ANE is based on characteristic symmetric lesions affecting the brain, detected by head computed tomography or magnetic resonance imaging, in a child with febrile illness as well as neurologic signs or symptoms with rapid neurologic decline. More feature descriptions for surveillance and diagnosis are available on the CDC website.