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.
Bisgard
Kristine M
KM
Bacterial Vaccine Preventable Diseases Branch, National Immunization Program, Centers for Disease Control and Prevention, Atlanta, GA, USA.
Pascual
F Brian
FB
Ehresmann
Kristen R
KR
Miller
Claudia A
CA
Cianfrini
Christy
C
Jennings
Charles E
CE
Rebmann
Catherine A
CA
Gabel
Julie
J
Schauer
Stephanie L
SL
Lett
Susan M
SM
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002353:Carrier State; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D018563:Disease Notification; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007115:Immunization Schedule; D015994:Incidence; D007223:Infant; D008297:Male; D008875:Middle Aged; D010567:Pertussis Vaccine / Q000008:administration & dosage; D018570:Risk Assessment; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology; D014917:Whooping Cough / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control
D010567:Pertussis Vaccine