Joinpoint regression analysis of pertussis crude incidence rates, Illinois, 1990-2014

Pertussis incidence has increased in recent years; we obtained incidence data from 1990-2014 from the Illinois Department of Public Health Web site. We analyzed the crude incidence rates using Joinpoint regression software. Four joinpoints were observed (2001, 2004, 2007, and 2012). Disease modeling can be used for disease control and planning by extrapolating the trend in the incidence data and applying to annual population estimates.