Human parainfluenza virus type 3 (HPIV-3, Human respirovirus 3) is the second most frequently detected virus after human respiratory syncytial virus (HRSV) in lower respiratory tract infections in children. HPIV-3, like its close relative respiratory viruses, HRSV and influenza virus, may cause encephalopathy, but the relevance of HPIV-3 as a pathogenic factor in encephalopathy is unknown. We attempted to detect HPIV-1 through 4, HRSV, and human metapneumovirus (HMPV) in 136 patients with encephalitis/encephalopathy, or suspected encephalitis/encephalopathy during a 6-year period from 2014 to 2019. As a result, HPIV-3 was detected most frequently in 6 patients, followed by HRSV in 3. The HPIV-3 strains detected were closely related to those detected in a patient with respiratory disease at the same period. Although HPIV-3 is less recognized than HRSV as a triggering virus of encephalopathy, our results suggest that HPIV-3 is at least as important as HRSV. Surveillance of the causative virus of encephalopathy, including HPIV-3, would help to clarify the actual status of encephalopathy, the cause of which is currently reported in less than half of cases in Japan.

人类副流感病毒 3 型（HPIV-3、人类呼吸道病毒 3）是儿童下呼吸道感染中第二常见的病毒，仅次于人类呼吸道合胞病毒 (HRSV)。HPIV-3与其近亲呼吸道病毒HRSV和流感病毒一样，可能引起脑病，但HPIV-3作为脑病致病因素的相关性尚不清楚。我们尝试在 2014 年至 2019 年 6 年间对 136 名脑炎/脑病或疑似脑炎/脑病患者中检测 HPIV-1 至 4、HRSV 和人偏肺病毒 (HMPV)。结果，HPIV-3 被检测出其中 6 例患者中检出最多的是 HRSV，其次是 3 例 HRSV。检测到的 HPIV-3 毒株与同期 1 例呼吸系统疾病患者中检测到的毒株密切相关。尽管 HPIV-3 不像 HRSV 那样被认为是脑病的触发病毒，但我们的结果表明 HPIV-3 至少与 HRSV 一样重要。对包括 HPIV-3 在内的脑病致病病毒进行监测将有助于澄清脑病的实际状况，目前日本只有不到一半的病例是由脑病引起的。