Prospective multinational study of pertussis infection in hospitalized infants and their household contacts.
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.
Kowalzik
Frank
F
University of Mainz, Mainz, Germany.
Barbosa
Arnaldo Prata
AP
Fernandes
Vera Regina
VR
Carvalho
Paulo Roberto
PR
Avila-Aguero
Maria Luisa
ML
Goh
Daniel Y T
DY
Goh
Anne
A
de Miguel
Jesus Garcia
JG
Moraga
Fernando
F
Roca
Joan
J
Campins
Magda
M
Huang
Ming
M
Quian
Jorge
J
Riley
Nicole
N
Beck
Dominique
D
Verstraeten
Thomas
T
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*