KEYWORDS:
Epidemiology, Surveillance, Pertussis, Incidence

BACKGROUND:
Pertussis, a highly infectious respiratory disease, continues to cause significant morbidity and mortality in the U.S. Reported cases are increasing primarily among infants <4 months and among adolescents.

OBJECTIVE(S):
To review the epidemiology of pertussis in 2000.

METHOD(S):
Pertussis is nationally reportable. Cases reported through the National Electronic Telecommunications System for Surveillance (NETSS) were included in the analysis.

RESULT(S):
Of 7,867 cases of pertussis reported during 2000, the incidence was 2.9/100,000 population. Among 7,839 cases with known age, 24% occurred among infants <6 months (incidence 98.8/100,000) too young to have received a three-dose primary series, 3% were among infants 6-11 months (incidence 11.5/100,000), 10% were among children 1-4 years (incidence 5.2/100,000), 8% were among children 5-9 years (incidence 3.15/100,000), 36% were among adolescents 10-19 years (incidence 7.0/100,000), and 20% were among adults ³20 years (incidence 0.8/100,000). Of 1,185 cases aged 6 months-6 years, 42% had received ³3 doses of pertussis-containing vaccine, 28% received 0-2 doses, and the vaccine history was unknown for 26%. There were 17 deaths in 2000 occurring in 12 states, all among infants <4 months.

CONCLUSIONS(S):
The highest reported rates of pertussis were among infants. The reasons that adolescents had higher reported rates of pertussis than children 1-9 years of age could include increased awareness among health-care providers, waning immunity 5-10 years after the last dose, and better reporting of cases to health departments. For both infants and adolescents the reason may be a true increase in circulating Bordetella pertussis.

LEARNING OBJECTIVES:
Understand the current epidemiology of pertussis morbidity and mortality among infants and among adolescents and adults.