I read with great interest the article by Kalita et al.1 In recent years, Japanese encephalitis (JE) has been well controlled with immunization in Taiwan, similar to Japan and Korea, as stated by Kalita and colleagues. Few Taiwanese children now develop JE; however, adult cases are increasing.
For children living in areas endemic to JE, especially Taiwan and Japan, acute necrotizing encephalopathy of childhood (ANEC) must be differentiated from JE using a neuroimaging point of view. Acute necrotizing encephalopathy of childhood manifests as acute encephalopathy following 2 to 4 days of fever and minor symptoms of the respiratory and/or gastrointestinal systems in infants and young children.2,3 Most cases have been reported in Taiwan and Japan. Although its pathogenesis is still uncertain, authors increasingly believe that some viruses, especially the influenza virus or its variants, start intracranial cytokine storms (usually within 24 to 48 hours) that cause damage to the blood-brain barrier in particular brain regions and result in localized edema and other pathologic changes such as congestion or hemorrhage, without signs of direct viral invasion or parainfectious demyelination.4
Wang H. Comparison of Magnetic Resonance Imaging Abnormalities in Japanese Encephalitis and Acute Necrotizing Encephalopathy of Childhood. Arch Neurol. 2004;61(7):1149-1150. doi:10.1001/archneur.61.7.1149