++
+++
Essentials of Diagnosis
++
Predominantly occurs in infants under age 2 years
Adolescents and adults are reservoir 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
+++
General Considerations
++
An acute infection of the respiratory tract caused by Bordetella pertussis, a gram-negative coccobacillus
Infection is transmitted by respiratory droplets
Neither immunization nor disease confers lasting immunity to pertussis
The diagnosis often is not considered in adults, who may not have a typical presentation; cough persisting more than 2 weeks is suggestive of pertussis
++
+++
Differential Diagnosis
++
Viral or bacterial pneumonia
Asthma
Other causes of chronic cough in adults
Bronchiolitis, eg, respiratory syncytial virus (children)
Croup (children)
++
The white blood cell count is usually 15,000–20,000/mcL (15–20 × 109/L) (rarely, as high as 50,000/mcL (50 × 109/L) or more), 60–80% of which are lymphocytes
The organism can be cultured from the nasopharynx using a special medium (eg, Bordet-Gengou agar)
++
Erythromycin, 500 mg four times daily orally for 7 days
Azithromycin, 500 mg once daily orally for 1 day, then 250 mg once daily for 4 days
Clarithromycin, 500 mg three times daily for 7 days
Trimethoprim-sulfamethoxazole 160 mg–800 mg orally twice a day for 7 days
Treatment shortens the duration of carriage and may diminish the severity of coughing paroxysms
++
Immunizations (Table 30–7)
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 > 64 years) should receive a single dose of Tdap
Pregnant women