Bordetella pertussis in sporadic and outbreak settings in Alberta, Canada, July 2004-December 2012.
BACKGROUND
ProvLab Alberta provides all laboratory testing for Bordetella pertussis including sporadic cases and outbreak investigations through collaborations with provincial public health partners. We describe B. pertussis activity in Alberta from July 2004 to December 2012.


METHODS
Laboratory testing for pertussis was analyzed using interpreted laboratory data that was generated by DIAL, a secure web-based platform. Duplicate specimens from the same individual ≤90 days were excluded to generate a case-based dataset. Immunization status of confirmed pertussis cases from the provincial immunization repository was reviewed.


RESULTS
Overall, 7.1% of suspected pertussis cases tested positive with a higher positivity rate in outbreak as compared to sporadic setting. Annual variations in sporadic pertussis cases were observed across the province with higher positivity rates in 2005, 2008, 2009 and 2012. A significantly higher positivity rate was observed in a northern region of Alberta. While the positivity rate in sporadic setting was highest in adolescents aged 10 to <15 years old (14.8%), population-based disease burden was highest in young children <5 years old. Of the 81.6% (n = 1,348) pertussis cases with immunization records, 48.3% were up-to-date with immunization. The pertussis cases that were up-to-date with their immunization were older (median age 12.9 years) as compared to those with incomplete (median age 9.7 years) or no pertussis immunization (median age 3.8 years).


CONCLUSIONS
Cyclic pattern of annual pertussis activity with geographic variation was observed in Alberta with no obvious case finding effect from outbreak investigations. The high positivity rates in adolescents suggested an underestimation of disease burden in this age group.
Sumana
S
Fathima
Christina
C
Ferrato
University of Alberta, Edmonton, AB, Canada. bonita.lee@albertahealthservices.ca.
Bonita E
BE
Lee
Kimberley
K
Simmonds
Lin
L
Yan
Shamir N
SN
Mukhi
Vincent
V
Li
Linda
L
Chui
Steven J
SJ
Drews
D000293:Adolescent; D000328:Adult; D000416:Alberta / Q000453:epidemiology; D001886:Bordetella pertussis / Q000302:isolation & purification*; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007114:Immunization; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D014611:Vaccination; D014917:Whooping Cough / Q000453:epidemiology*; D055815:Young Adult