To the Editor: According to the Centers for Disease Control and Prevention, 5%−20% of the US population is infected by the influenza virus annually. The influenza virus commonly affects the respiratory system, but the neuropsychiatric symptoms are often underappreciated. Karl Menninger was one of the first to link neuropsychiatric symptoms in 100 patients with influenza who were admitted with behavioral changes in 1918.1 The famous 1918 strain of influenza was associated with von Economo’s encephalitis lethargica and postencephalitic parkinsonism.2 In the 1960s, pediatric cases of influenza infections were associated with Reye’s syndrome.2 The influenza A 2009 strain was coupled with an increase in the number of serious cases of acute necrotizing encephalopathy.2Primary neurological manifestations appear more commonly in children but can emerge in adults with symptoms of headaches, numbness, paresthesia, weakness, vertigo, decreased alertness, seizures, encephalopathy, and meningismus. Other less common neurologic complications include Guillain-Barré syndrome, aseptic meningitis, and transverse myelitis.2,3 The influenza virus has also been associated with acute psychosis and the onset of a manic episode.4–6 The following report illustrates a case of a patient with suspected influenza-induced mania.
A 60-year-old man with no significant past medical or psychiatric history presented with new-onset paranoia, religious preoccupation, and mood fluctuations after a severe upper respiratory infection. The psychiatry department was consulted after the patient’s admission to the medical floor. He exhibited symptoms of mania with euphoric mood, mood lability, pressured speech, decreased need for sleep, increased energy, and flight of ideas. He had grandiose delusions of being a prophet, had “prophetic visions,” and thought he could see the future. Information from his family revealed that just before the onset of his manic symptoms the patient was suffering from an upper respiratory infection in mid-January. For 2 weeks, he exhibited myalgia, fatigue, fever, cough, insomnia, and weight loss. He did not utilize any medications, and the family started to notice concerning behavioral changes as the respiratory symptoms were improving.
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