Influenza Infection Causing Manic Psychosis

Although depression is well known as a sequel to influenza, mania is not. We describe a patient with a severe psychotic illness who first showed features of a confusional state but then developed a manic psychosis. The occurrence of functional affective psychoses during or following systemic physical illness has been well described (Bonhoeffer, 1909; Kraepelin, 1921; Kiloh, 1961; Post, 1965), but the nature of the relationship has never been clear. In some instances, the physical illness may simply act as a form of non-specific stress precipitating the mental disorder; evidence for a more direct patho-physiological relationship has been lacking. When, in addition to a background of physical illness, a patient shows disorientation and clouding of consciousness together with signs of a manic psychosis, the diagnostic problem is especially difficult, particularly so since a confusional state can occur as part of a severe manic illness (Maudsley, 1895; Kraepelin, 1921). Conversely, hypomanic symptoms can occur in an organic psychosis (Bonhoeffer, 1909).