Pertussis
Kenan Haver, MD, FAAP
Introduction/Etiology/Epidemiology
•Pertussis, or whooping cough, is an acute infectious disease caused by the bacterium Bordetella pertussis.
•The first observation of pertussis occurred in France in 1414, and the first epidemic was noted in Paris in 1578; B pertussis was first isolated in 1906.
•Pertussis remains a major health problem among children in developing countries, with 195,000 deaths resulting from the disease reported
in 2008. Even in the United States, pertussis remains a public health problem. In 2012, 48,277 cases of pertussis were reported to the U.S. Centers for Disease Control and Prevention (CDC), including 20 pertussis-related deaths.
•Transmission occurs via aerosolized droplets of respiratory secretions.
—Adolescents and adults are an important reservoir for B pertussis and are often the source of infection for infants.
—No animal or insect source or vector is known to exist.
Pathophysiology
•B pertussis is an aerobic gram-negative rod.
•The bacteria attach to the cilia of the respiratory epithelial cells, produce toxins that paralyze the cilia, and cause inflammation of the respiratory tract, which interferes with the clearing of pulmonary secretions. Pertussis antigens appear to allow the organism to evade host defenses. An immune response to 1 or more antigens produces immunity after infection.
•Pertussis is highly communicable, as evidenced by secondary attack rates of 70%–100% among susceptible household contacts. Persons with pertussis are most infectious during the catarrhal period and the first 2 weeks after cough onset (ie, approximately 21 days).
Clinical Features
•Disease progression is shown in Figure 50-1.
•The incubation period lasts 7–10 days (range, 4–21 days). — It has insidious onset, similar to the common cold, with nonspecific cough.
Figure 50-1. Disease progression in pertussis. From https://www.cdc.gov/pertussis/about/signs-symptoms.html.
•Fever is usually minimal throughout the course of illness.
•The catarrhal stage (maximum communicability) lasts 1–2 weeks.
—Coryza
—Low-grade fever
—Occasional cough
•The paroxysmal cough stage lasts 1–6 weeks.
—Minimal fever
—There are paroxysms of numerous, rapid coughs, apparently due to difficulty in expelling thick mucus from the tracheobronchial tree. At the end of the paroxysm, a long inspiratory effort is usually accompanied by a characteristic, high-pitched whoop.
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