Epidemiology and surveillance of pertussis among infants in Catalonia, Spain, during 1997-2001.
BACKGROUND
Despite high levels of vaccination coverage in Spain and Catalonia (98% in 2002), pertussis is a significant cause of morbidity among infants. The study aim was to estimate the incidence of hospitalizations for pertussis among infants from 1997 through 2001 in Catalonia.


METHODS
A retrospective review of records for patients <12 months of age with a diagnosis of pertussis (International Classification of Diseases, 9th revision, code 033) at discharge from 11 Catalonian hospitals was performed.


RESULTS
Three hundred forty-six patients were identified, 62 (1997), 28 (1998), 59 (1999), 150 (2000) and 47 (2001), of whom 284 (82%) were <4 months of age. The incidence of hospitalizations because of whooping cough from 1997 through 2001 in Catalonia was estimated at 118 cases per 100,000 inhabitants <12 months of age. Symptoms included paroxysmal cough (95%), cyanosis (67.9%), vomiting (36.7%) and apneic episodes (27.7%). Three infants (0.8%) died, all <2 months of age. Two hundred thirty-four patients (67.6%) were unvaccinated (222 patients were <3 months of age). Six patients (1.7%) were fully vaccinated (3 doses). Considering that only 220 patients <12 months of age were reported through the Catalonian Notification System in 1997-2001, at least 126 hospitalizations (36.4%) for pertussis were not reported to this system (mean difference per year, 32.6%; range, 8.4-56%).


CONCLUSIONS
In this study, hospitalizations exceeded the number of notifications by at least 32.6%; therefore, the real incidence is likely to be greatly underestimated. Pertussis incidence remains high among infants, most of whom are <4 months of age and have had no or 1 dose of vaccine.
Moraga
Fernando
F
Vall d'Hebron Hospital, Barcelona, Spain. fmoraga@acmcb.es
Roca
Joan
J
Méndez
Cristina
C
Rodrigo
Carlos
C
Pineda
Valentí
V
Martinez
Antoni
A
Baraibar
Romà
R
Boronat
Mercedes
M
D001886:Bordetella pertussis / Q000302:isolation & purification; D018563:Disease Notification / Q000706:statistics & numerical data; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010567:Pertussis Vaccine / Q000008:administration & dosage; D011159:Population Surveillance; D013030:Spain / Q000453:epidemiology; D014611:Vaccination; D022282:Vaccines, Acellular / Q000008:administration & dosage; D014917:Whooping Cough / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control
D010567:Pertussis Vaccine; D022282:Vaccines, Acellular