BACKGROUND: To address changing diagnostic practices and significant numbers of PCR positive infant cases not meeting the required clinical criteria, the CSTE/CDC pertussis case definition was modified in 2014. Using both the 2014 and previous CDC/CSTE case definition, the Georgia Department of Public Health sought to determine the effect of this change on the burden of pertussis disease among infants between 2010 and 2015 using notifiable disease surveillance in GA.
METHODS: Using the State Electronic Notifiable Disease Surveillance System (SendSS), infants reported with cough onset between 1/1/2010 - 12/31/2013 and classified as not- a- case (NAC) were re-evaluated utilizing the 2014 CSTE/CDC pertussis case definition. Infant cases with cough onset between 1/1/2014 and 12/31/2015 were also reassessed to determine whether they would have been classified as NAC prior to the implementation of the 2014 case definition.
RESULTS: Between 2010 and 2013, 89 infants were classified as NAC. Forty-five (50.5%) of these infants would have been classified as cases using the 2014 CSTE/CDC case definition, which represents an 11.4% increase in the number of infant cases during this time, and captures two additional pertussis-related deaths . From 2014-2015, only 8 infants (preliminary), who would have previously been classified as NAC, were classified as cases.
CONCLUSIONS: Use of the 2014 case definition improves the sensitivity of pertussis surveillance by capturing infants with atypical presentations and/or cough duration < 14 days. Limitations of the previous case definition may have resulted in an underestimation of pertussis among infants in Georgia.