The 'flu-like illness.
D000293:Adolescent; D000328:Adult; D000368:Aged; D001424:Bacterial Infections / Q000175:diagnosis; D003937:Diagnosis, Differential; D004739:England; D005260:Female; D006801:Humans; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009975:Orthomyxoviridae; D010507:Periodicity; D014777:Virus Diseases / Q000453:epidemiology*