title: Pertussis in Bulgaria, 1952-2001: 50 years of surveillance.
mesh_terms: D001886:Bordetella pertussis; D002031:Bulgaria / Q000453:epidemiology; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000517:prevention & control; D006801:Humans; D017589:Immunization Programs; D007223:Infant; D010567:Pertussis Vaccine / Q000008:administration & dosage*; D011159:Population Surveillance; D014917:Whooping Cough / Q000453:epidemiology* / Q000517:prevention & control*
chemical_list: D010567:Pertussis Vaccine