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Article Excerpt
ABSTRACT: Since pertussis has been considered to be primarily a pediatric disease, it is often overlooked as a cause of cough in adults. However, the incidence has been increasing in adolescents and adults, and these persons are the major reservoir for the disease. The first stage of illness is characterized by flu-like symptoms; then patients typically have paroxysms of severe coughing--several short dry coughs, followed by a deep inspiratory effort and the characteristic "whoop." The most common complication of pertussis is pneumonia, but other complications include bronchitis, laryngitis, atelectasis, pneumothorax, subconjunctival hemorrhage, subdural hematoma, and seizures. The diagnosis can be confirmed by isolation of Bordetella pertussis in culture; rapid diagnostic tests, such as the direct fluorescent antibody method and polymerase chain reaction; and serological tests to detect antibodies to B pertussis. First-line therapy for pertussis includes a macrolide antibiotic.
KEY WORDS: Pertussis, Pediatric infectious disease, Vaccines
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Pertussis is a serious respiratory infection that was first described in the 1500s. The original description of the clinical syndrome of pertussis is credited to Guillaume de Baillou during an epidemic in Paris in 1578. (1) Thomas Sydenham first used the term "pertussis," meaning intense cough, in 1670. (2) The bacterium that causes pertussis was first identified and cultured at the Pasteur Institute by Jules Bordet and Octave Gengou in 1906. (3) Originally named Haemophilus pertussis, it was renamed Bordetella pertussis in honor of Bordet.
In this article, I will review the epidemiology, clinical presentation, diagnosis, and treatment of pertussis.
Epidemiology
In the 1930s and 1940s, the annual incidence of pertussis in the United States was approximately 150 per 100,000 population, and the case fatality rate was 4%. (4) After the development of a whole-cell vaccine and the introduction of infant immunization programs in 1950, the incidence of pertussis and the mortality associated with it decreased to 1 case and less than 0.01 deaths per 100,000, respectively, by the mid-1970s. (5)
Immunization with an acellular pertussis vaccine was started in 1981. (4) However, lax implementation of policy resulted in epidemic pertussis in many states in 1989 to 1990, 1993, 1996, and 2003. More than 7500 cases were reported to the CDC in 1996, and 11,647 cases were reported in 2003; this was the highest incidence since 1967. (2,6)
There is good evidence that pertussis is underdiagnosed and underreported. (2) The number of cases per year in the United States has been reported to be as low as 1200 to 4000 (7) and as high as 6000 to 8000. (2) In developing countries, pertussis is a major cause of morbidity and mortality, and annual rates may reach 200 to 500 per 100,000 persons, with 350,000 deaths among children younger than 5 years. (8,9) An outbreak of pertussis was reported in Afghanistan in 2003. (10)
Previously, pertussis was considered to be primarily a disease of infants and young children. In 1992, about 50% of reported cases in the United States occurred in children younger than 1 year, and 75% occurred in children younger than 5 years. (5) Now, about 67% of cases occur in adolescents and adults; in these persons, pertussis is not usually recognized as the cause of their cough. These adolescents and adults currently are the major reservoir for the disease and are the usual sources for "index cases" in infants and children. (2)
Pathophysiology
Pertussis is characterized by a pattern of endemic activity with cyclic periodic epidemics that occur on average every 3 years and last 12 to 18 months. Infection is most common during the late spring and summer. (5) Pertussis is a highly communicable disease, with attack rates up to 90% in exposed susceptible persons, such as those who have not received a full series of pertussis vaccinations and those whose vaccine-induced immunity has waned.
The organism is acquired by person-to-person contact and enters through the respiratory tract. The incubation period ranges from 5 to 21 days, with an average of 7 days. In the absence of treatment, the infectivity period extends from 7 days after exposure until 3 weeks after the onset of paroxysms of coughing. (4)
B pertussis, the major cause of the pertussis syndrome, is a Gramnegative, pleomorphic, nonmotile coccobacillus. It produces a number of virulence factors. Filamentous...
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