Figure 2

Temporal Trends in Pertussis Testing and Estimated Crude Pertussis Incidence, Greater Toronto Area, Canada, 1993-2007. Cumulative weekly tests are presented as gray bars; annualized pertussis rates are presented as rates per million rather than per 100,000 (as in text) to maintain comparability of scales. Dashed lines represent initial introduction of PCR testing (January 1999) and introduction of more sensitive PCR assay (May 2005). It can be seen that there is a strong correlation between specimen submission and estimated pertussis incidence.