Oseltamivir treatment for children showing abnormal behavior during influenza virus infection

We investigated the clinical courses of children with influenza infection, who showed abnormal behavior, who were treated with oseltamivir (Tamiflu®). Subjects: The subjects were 22 children, 2–15 (mean ± SD, 6.6 ± 3.2) years old, admitted to our hospital during the 2004–2005, 2005–2006, and 2006–2007 influenza seasons. Abnormal behavior appeared before treatment with oseltamivir in 13 children (pre-Tami group), and after administration of the medication in 9 (post-Tami group). All patients continued to receive oseltamivir for 3–5 days after admission. Results: Meaningless speech and movements without a specific purpose were the most frequent abnormal behavior (16 children), while illusions, delusions, and misidentifying awareness were the second most common (14 children). Sensations of marked fear and excitement were recognized in 6 children. One child rushed up and down the stairs unconsciously, raising concern that a serious accident might occur. All patients showed a favorable clinical course, without worsening of neurological symptoms or the development of encephalopathy, and outcomes were good. The clinical course, number of recurrences of abnormal behavior, and outcome were similar in the pre-Tami and post-Tami groups. Conclusions: Our observations suggest that oseltamivir is not a prerequisite for the development of abnormal behavior and does not worsen the clinical manifestations of abnormal behaviors, although further investigations are needed to determine whether oseltamivir is necessary, or even useful, for patients with influenza virus encephalopathy.