Pertussis, Bordetella

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

Demographics

• Pertussis causes high morbidity and mortality in many countries

• Incidence of pertussis has increased steadily since the 1980s

Symptoms and Signs

• Symptoms of classic pertussis last about 6 weeks and are divided into three consecutive stages

• The catarrhal stage

  • Characterized by its insidious onset

  • Lacrimation, sneezing, and coryza, anorexia, and malaise

  • Hacking night cough that tends to become diurnal

• The paroxysmal stage

  • Characterized by bursts of rapid, consecutive coughs followed by a deep, high-pitched inspiration (whoop)

• The convalescent stage

  • Usually begins 4 weeks after onset of the illness with a decrease in the frequency and severity of paroxysms of cough

Differential Diagnosis

• Viral or bacterial pneumonia

• Asthma

• Other causes of chronic cough in adults

  • Postnasal drip

  • Gastroesophageal reflux disease

  • Tuberculosis

  • Mycobacterium avium complex

• Bronchiolitis, eg, respiratory syncytial virus (children)

• Croup (children)

• The white blood cell count is usually 15,000–20,000/mcL (rarely, as high as 50,000/mcL 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

Prevention

• 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

  • Should receive a dose of Tdap during each pregnancy regardless of prior vaccination history, ideally between 27 and 36 weeks of gestation to maximize the antibody response of the pregnant woman and the passive antibody transfer to the infant

  • Tdap should be administered immediately postpartum for any woman who was not previously vaccinated with Tdap and for whom the vaccine was not given during her pregnancy

• The CDC has eliminated the recommendation for a 2-year period window between receiving the Td and Tdap vaccines based on data showing that there is no increased risk of adverse events

When to Refer

• Pertussis must be reported to the public health authorities

When to Admit

• Adults must be admitted if respiratory insufficiency (eg, hypoxia) is present