title: Characteristics of pertussis outbreaks in Catalonia, Spain, 1997 to 2010.
abstract: In Catalonia, pertussis outbreaks must be reported to the Department of Health. This study analyzed pertussis outbreaks between 1997 and 2010 in general and according to the characteristics of the index cases. The outbreak rate, hospitalization rate and incidence of associated cases and their 95%CI were calculated. Index cases were classified in two groups according to age (&lt;15 years and ≥15 years) and the vaccine type received: whole cell vaccine (DTwP) or acellular vaccine (DTaP). During the study period, 230 outbreaks were reported. The outbreak rate was 2.43 × 10(-6) persons-year, and outbreaks ranged from 2 to 32 cases, with a median duration of 18 days. There were 771 associated cases, with an incidence rate of 0.8 × 10(-5) persons-year.   After classifying outbreaks according to the age of the index case, 126 outbreaks (1.3 × 10(-6) persons-year) had an index case aged &lt;15 y and 87 (0.87 × 10(-6) person-year) had an index case aged ≥15 y (RR = 1.44, 95%CI 1.10-1.90; P = 0.007). Between 2003 and 2010, after the introduction of the acellular vaccine, the index case was vaccinated with DTwP vaccine in 25 outbreaks (0.43 × 10(-6) persons-year) and with DTaP vaccine in 32 outbreaks (0.55 × 10(-6) person-year) (RR = 0.78, 95%CI 0.46-1.31; P = 0.35). Of cases, 37.2% were correctly vaccinated, suggesting waning immunity of pertussis vaccine protection and endogenous circulation of pertussis. A greater number of outbreaks had an index case aged &lt;15 y. No changes in the disease incidence, associated cases and hospitalization rate were observed after the introduction of DTaP.
authors.affiliation: a CIBER Epidemiología y Salud Pública; Carlos III Institute of Health; Madrid, Spain.
authors.forename: Inma
authors.initials: I
authors.lastname: Crespo
authors.forename: Sonia
authors.initials: S
authors.lastname: Broner
authors.forename: Núria
authors.initials: N
authors.lastname: Soldevila
authors.forename: Ana
authors.initials: A
authors.lastname: Martínez
authors.forename: Pere
authors.initials: P
authors.lastname: Godoy
authors.forename: Maria-Rosa
authors.initials: MR
authors.lastname: Sala-Farré
authors.forename: Maria
authors.initials: M
authors.lastname: Company
authors.forename: Cristina
authors.initials: C
authors.lastname: Rius
authors.forename: Angela
authors.initials: A
authors.lastname: Domínguez
authors.forename: The Pertussis Working
authors.initials: TP
authors.lastname: Group Of Catalonia
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D008875:Middle Aged; D010567:Pertussis Vaccine / Q000008:administration & dosage; D013030:Spain / Q000453:epidemiology; D014611:Vaccination / Q000379:methods; D014917:Whooping Cough / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D010567:Pertussis Vaccine
keywords: acellular pertussis vaccine; hospitalization; pertussis; surveillance; whole cell pertussis vaccine