Infant pertussis: who was the source?

BACKGROUND: In the United States in the 1990s, the incidence of reported pertussis in adults, adolescents and infants increased; infants younger than 1 year of age had the highest reported incidence. METHODS: In 4 states with Enhanced Pertussis Surveillance, we examined the epidemiology of reported pertussis cases to determine the source of pertussis among infants. A source was defined as a person with an acute cough illness who had contact with the case-infant 7-20 days before the infant's onset of cough. RESULTS: The average annual pertussis incidence per 100,000 infants younger than 1 year of age varied by state: 22.9 in Georgia; 42.1 in Illinois; 93.0 in Minnesota; and 35.8 in Massachusetts. Family members of 616 (80%) of 774 reported case-infants were interviewed; a source was identified for 264 (43%) of the 616 case-infants. Among the 264 case-infants, mothers were the source for 84 (32%) and another family member was the source for 113 (43%). Of the 219 source-persons with known age, 38 (17%) were age 0-4 years, 16 (7%) were age 5-9 years, 43 (20%) were age 10-19 years, 45 (21%) were age 20-29 years and 77 (35%) were age > or =30 years. CONCLUSIONS: The variation in reported pertussis incidence in the 4 states might have resulted from differences in awareness of pertussis among health care providers, diagnostic capacity and case classification. Among case-infants with an identifiable source, family members (at any age) were the main source of pertussis. Understanding the source of pertussis transmission to infants may provide new approaches to prevent pertussis in the most vulnerable infants.

Disease surveillance and the academic, clinical, and public health communities.

The Emerging Infections Programs (EIPs), a population-based network involving 10 state health departments and the Centers for Disease Control and Prevention, complement and support local, regional, and national surveillance and research efforts. EIPs depend on collaboration between public health agencies and clinical and academic institutions to perform active, population-based surveillance for infectious diseases; conduct applied epidemiologic and laboratory research; implement and evaluate pilot prevention and intervention projects; and provide capacity for flexible public health response. Recent EIP work has included monitoring the impact of a new conjugate vaccine on the epidemiology of invasive pneumococcal disease, providing the evidence base used to derive new recommendations to prevent neonatal group B streptococcal disease, measuring the impact of foodborne diseases in the United States, and developing a systematic, integrated laboratory and epidemiologic method for syndrome-based surveillance.