An epidemiological study of postviral olfactory disorder.

Postviral olfactory disorder develops after infection with the common cold, and is a relatively severe and prolonged disorder without rhino-sinusitis. This epidemiological study aimed to characterize its clinical pathology and determine the causative virus. Postviral olfactory disorder occurs most commonly in middle-aged women and is most prevalent in spring and summer. A comparison of the monthly frequency of the disorder with the incidence of isolation of various viruses suggest that the influenza virus, respiratory syncytial virus, and herpes virus are not causative viruses, while parainfluenza virus type 3 is most likely to be a causative virus. This conclusion is supported by immunological study and analysis of symptoms of the cold. All patients with postviral olfactory disorder had increased serum antibody titre for parainfluenza virus type 3. No prominent or specific symptoms of common cold were identified as a potential trigger of this syndrome in patient questionnaires.