Influenza.
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D005060:Europe / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007223:Infant; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology*; D012621:Seasons