In 1999,7,288 cases of pertussis were reported to the Centers for Disease Control and Prevention (CDC).1 High rates of pertussis, compared with other pediatric vaccinepreventable diseases, continued to occur even though, since 1995, the coverage rate with at least three doses of a pertussis-containing vaccine has been greater than 95% among US children aged 19 to 35 months.
2The continuing high rates of pertussis in the United States pose a challenge for infection control professionals to develop new strategies to recognize and manage nosocomial outbreaks of pertussis. In this issue, Martinez and colleagues describe a hospitalwide outbreak of a Bordetella pertussis-like illness and report that the use of postexposure prophylaxis with azithromycin was tolerated well and resulted in few healthcare workers (HCWs) missing work.
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C H A N G I N G EPIDEMIOLOGY OF PERTUSSIS: IMPORTANCE OF I N F E C T I O N I N ADULTSSince 1980, the number of reported cases of pertussis has increased in the United States. Possible reasons for this rise could include increased awareness of pertussis among healthcare providers, increased use of more sensitive diagnostic tests, and better reporting of cases to health departments.1 Because vaccine-induced immunity wanes within 5 to 10 years after pertussis vaccination, most adolescents and adults are susceptible to disease. 45 In contrast to the period 1990 through 1993, during 1994 through 1996, the incidence of pertussis reported to the CDC among preschool-aged children did not change, but the incidence among adolescents aged 10 to 19 years and adults increased by more than 90%. 6 An analysis of surveillance data from 1989 to 1998 in Massachusetts also noted that the incidence in children remained stable, whereas the incidence in adolescents and adults increased; indeed, by 1998, 92% of cases occurred in adolescents and adults.
7Pertussis is increasingly recognized as a case of chronic cough in adults.
"11 Serological studies of prolonged cough illnesses in US adolescents and adults indicated that between 12% and 26% result from B pertussis infection.1215 Studies in other developed countries have produced similar results.11 The varying incidence rates reported depend, in part, on differences in study populations (eg, age), clinical definitions of disease (eg, duration of cough), and laboratory criteria for diagnosis.
16Pertussis in young children remains a serious disease. Common complications include pneumonia, 9.4%; seizures, 2.3%; and encephalopathy, 0.5%. Death occurred in 0.9% of children, all under 6 months of age.17 Adults with pertussis frequently experience prolonged cough, sleep disturbed by cough, and cough followed by choking or vomiting. 18 Complications have been reported to be more common in adults than adolescents (28% vs 16%), with pneumonia occurring in 5% to 9% of persons older than 30 years of age.19 Subclinical pertussis may be common in adults with household exposure.
20Adolescents and young adults play an important role in the transmission of pertussis, because immu...