Bordetella pertussisin sporadic and outbreak settings in Alberta, Canada, July 2004 – December 2012

Abstract

BackgroundProvLab 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.MethodsLaboratory 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.ResultsOverall, 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).ConclusionsCyclic 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.

Dominance of two genotypes of Bordetella pertussis during a period of increased pertussis activity in Alberta, Canada: January to August 2012

“…1,2 The selection of B. pertussis isolates for genotyping was as follows. Viable B. pertussis-positive culture isolates and cases were first linked and then isolates from known household contacts of first cases were excluded.…”

“…The previous 5-year average for the same time period was 89.4 cases, and in the South and Edmonton zones the number of cases was 3 and 5 times as high, respectively. 1 Various causes for this increase were postulated, including non-vaccination, waning immunity, the relatively high sensitivity of Bordetella pertussis molecular testing platforms, and potential primary vaccine failure. Although vaccination status and molecular typing of isolates has been discussed in prior studies, little has been done to directly link vaccine status to genotype.…”

Pertussis: Microbiology, Disease, Treatment, and Prevention

“…Pertussis outbreaks have been also reported in North America, Europe, and Australia (182,195,202,203,254,264,(435)(436)(437)(438). In contrast, few data are available from Latin American, Asian, and African countries compared with Europe and the United States (174,(439)(440)(441)(442)(443)(444)(445)(446).…”

Characteristics of pertussis outbreaks in Catalonia, Spain, 1997 to 2010

“…26 However, a Canadian study found a greater number of pertussis outbreaks during the winter (November to March). 23 Our results show differences according to sex in some age groups. The 25-44 y age group included a higher percentage of women who had recently been mothers or who had continuous contact with infants.…”

“…This may be explained by waning immunity, as suggested by other reports. [22][23][24] From 2003 onwards, the age distribution of affected cases show highest incidence in infants aged <1 y. Before 2003, the incidence according to age groups showed a different pattern.…”