title: Prospective multinational study of pertussis infection in hospitalized infants and their household contacts.
abstract: BACKGROUND
  Increased incidence of pertussis has been noted among infants too young to be immunized. We studied the disease burden of pertussis in pediatric intensive care units and the source of infection in several Asian, European and Latin American countries.
  
  
  METHODS
  The study was conducted in 7 countries from September 2001 to January 2004. Children <1 year of age were enrolled from pediatric intensive care units (PICU) and pediatric wards if they presented with respiratory failure, apnea, bradycardia, or cough accompanied by paroxysms, vomiting, whoop or cyanosis. Household members of pertussis-positive index cases were asked to answer a questionnaire and provide diagnostic specimens.
  
  
  RESULTS
  Pertussis was confirmed in 99 infants (12%) of 823 infants included in the analysis: 10 of 90 (11%) in Brazil, 9 of 88 (10%) in Costa Rica, 11 of 145 (8%) in Germany, 13 of 147 (9%) in Singapore, 29 of 67 (43%) in Spain, 2 of 86 (2%) in Taiwan and 25 of 200 (13%) in Uruguay. However, sensitivity analysis indicated that these figures were conservative. The mean (+/- SD) average age of infection was 2.6 +/- 2.2 months. Pertussis was found among 96 of 269 (36%) of household contacts investigated. At least one household contact was identified as the source of infection in 24 of 88 (27%) of the PICU cases and mothers were identified as being the most frequent source of infection.
  
  
  CONCLUSIONS
  Although regional differences exist, severe pertussis represents a considerable global disease burden. Since most infants are infected before vaccination and concomitant protection is completed, household contacts should be targeted for booster vaccination to reduce the pertussis reservoir.
authors.affiliation: University of Mainz, Mainz, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Kowalzik
authors.forename: Arnaldo Prata
authors.initials: AP
authors.lastname: Barbosa
authors.forename: Vera Regina
authors.initials: VR
authors.lastname: Fernandes
authors.forename: Paulo Roberto
authors.initials: PR
authors.lastname: Carvalho
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Avila-Aguero
authors.forename: Daniel Y T
authors.initials: DY
authors.lastname: Goh
authors.forename: Anne
authors.initials: A
authors.lastname: Goh
authors.forename: Jesus Garcia
authors.initials: JG
authors.lastname: de Miguel
authors.forename: Fernando
authors.initials: F
authors.lastname: Moraga
authors.forename: Joan
authors.initials: J
authors.lastname: Roca
authors.forename: Magda
authors.initials: M
authors.lastname: Campins
authors.forename: Ming
authors.initials: M
authors.lastname: Huang
authors.forename: Jorge
authors.initials: J
authors.lastname: Quian
authors.forename: Nicole
authors.initials: N
authors.lastname: Riley
authors.forename: Dominique
authors.initials: D
authors.lastname: Beck
authors.forename: Thomas
authors.initials: T
authors.lastname: Verstraeten
mesh_terms: D001938:Brazil / Q000453:epidemiology; D016358:Contact Tracing; D003364:Costa Rica / Q000453:epidemiology; D005191:Family Characteristics; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012846:Singapore / Q000453:epidemiology; D013030:Spain / Q000453:epidemiology; D013624:Taiwan / Q000453:epidemiology; D014583:Uruguay / Q000453:epidemiology; D014917:Whooping Cough / Q000453:epidemiology*