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Essentials of Diagnosis
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Predominantly occurs in infants under age 2 years
Adolescents and adults are reservoirs of infection
Two-week prodromal catarrhal stage of malaise, cough, coryza, and anorexia
Paroxysmal cough ending in a high-pitched inspiratory "whoop"
Absolute lymphocytosis, often striking; nasopharyngeal culture confirms diagnosis
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General Considerations
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An acute infection of the respiratory tract caused by Bordetella pertussis, a gram-negative coccobacillus
Infection is transmitted by respiratory droplets
The incubation period is 7–17 days
Cough persisting more than 2 weeks is suggestive
Neither immunization nor disease confers lasting immunity to pertussis, requiring ongoing vaccination
Atypical presentations are more common in adults and individuals who were previously vaccinated
Infection may be asymptomatic, and apnea may be the only manifestation in infants
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Differential Diagnosis
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Viral or bacterial pneumonia
Asthma
Other causes of chronic cough in adults
Bronchiolitis, eg, respiratory syncytial virus (children)
Croup (children)
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The white blood cell count is usually 15,000–20,000/mcL (15–20 × 109/L) with a lymphocytosis
The organism can be cultured from the nasopharynx using a special medium (eg, Bordet-Gengou agar)
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Azithromycin, 500 mg orally on day 1, then 250 mg orally once daily for 4 days
Clarithromycin, 500 mg orally twice daily for 7 days
Trimethoprim-sulfamethoxazole, 160–800 mg orally twice daily for 14 days
Treatment shortens the duration of carriage and may diminish the severity of coughing paroxysms
Same regimens are indicated for prophylaxis of contacts to an active case of pertussis who are exposed within 3 weeks of the onset of cough in the index case
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Immunizations (Table 32–7)
Acellular pertussis vaccine is recommended for all infants, combined with diphtheria and tetanus toxoids (DTaP)
Infants and susceptible adults with significant exposure should receive prophylaxis with an oral macrolide
Adults of all ages (including those older than 64 years) should receive a single dose of Tdap
Pregnant women