title: Epidemics of parapertussis. 20 years' observations in Denmark.
mesh_terms: D000367:Age Factors; D001886:Bordetella pertussis / Q000302:isolation & purification; D002648:Child; D002675:Child, Preschool; D003718:Denmark; D004196:Disease Outbreaks; D006801:Humans; D007223:Infant; D014917:Whooping Cough / Q000453:epidemiology*