title: Pertussis infection in adults with persistent cough.
abstract: OBJECTIVE
  To determine the prevalence of Bordetella pertussis infection in adult patients with persistent cough.
  
  
  METHODS
  Prospective case series.
  
  
  METHODS
  Urban university hospital emergency department.
  
  
  METHODS
  Convenience sample of 75 patients aged 18 years or older with a cough lasting 2 weeks or longer. Serum specimens from 67 patients without respiratory complaints were used to develop reference values.
  
  
  METHODS
  In patients with cough, nasopharyngeal culture and direct fluorescent antibody testing for B pertussis were performed and serum samples were obtained at the first visit and 1 month later. Serum specimens were assayed for antibody to pertussis toxin (PT) and filamentous hemagglutinin (FHA).
  
  
  METHODS
  A subject with one or more of the following was defined as having a pertussis infection: a positive B pertussis culture result, a four-fold change in PT or FHA titer, and/or a single PT or FHA titer at least 2 SDs greater than the geometric mean of the control group.
  
  
  RESULTS
  No subject tested culture positive for B pertussis. Sixteen (21%) (95% confidence interval [CI], 13% to 32%) of 75 subjects met the serologic criteria for pertussis infection; for 13 (81%; 95% CI, 54% to 96%) of the 16, the criteria were met by the initial serum specimen. In contrast, the geometric mean levels of antibody to PT and FHA for the remaining 59 subjects with cough did not differ from those of the control group. Clinical symptoms and the lymphocyte count did not differentiate patients with pertussis from those without the disease.
  
  
  CONCLUSIONS
  Pertussis is a common cause of persistent cough in adults and should be considered in the differential diagnosis. Clinical symptoms, pertussis culture, direct fluorescent antibody testing, and lymphocytosis are of limited value in making the diagnosis.
authors.affiliation: Department of Emergency Medicine, Vanderbilt University Medical Center, Nashville, TN 37232-4700, USA.
authors.forename: S W
authors.initials: SW
authors.lastname: Wright
authors.forename: K M
authors.initials: KM
authors.lastname: Edwards
authors.forename: M D
authors.initials: MD
authors.lastname: Decker
authors.forename: M H
authors.initials: MH
authors.lastname: Zeldin
mesh_terms: D000328:Adult; D001886:Bordetella pertussis / Q000302:isolation & purification; D003371:Cough / Q000209:etiology; D003937:Diagnosis, Differential; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008218:Lymphocytosis; D008297:Male; D009305:Nasopharynx / Q000382:microbiology; D015995:Prevalence; D011446:Prospective Studies; D012016:Reference Values; D012698:Serologic Tests; D014917:Whooping Cough / Q000175:diagnosis* / Q000453:epidemiology*