Pertussis Trends in Texas, 2005-2009

Background: Surveillance for pertussis in Texas began in the 1920s.  After the introduction of vaccines to protect against pertussis in the 1940s, Texas saw a dramatic decline in disease.  A resurgence of pertussis has arisen in the last decade.  Within the last five years, pertussis in Texas reached an incidence rate that had not been seen in approximately 40 years (10 cases per 100,000 population).

Objectives: To describe the recent trends in the epidemiology of pertussis in Texas over the last 5 years, from 2005-2009.   

Methods: Investigations of pertussis cases are prompted through electronic reporting of laboratory results, telephone calls, and reports from medical providers.  Public health department staff then conduct pertussis disease investigations which is then entered into an electronic surveillance system.  Pertussis surveillance data from 2005-2009 was abstracted and descriptive statistical data analysis utilizing SAS software was conducted.  GIS statistical mapping software was also used to illustrate the distribution of disease throughout the state.

Results: Over the 5-year period, the highest statewide incidence rate (cases per 100,000 population) was in 2005 with 9.7 (n=2224).  The lowest statewide incidence rate over this time frame was in 2006 with 4.1 (n=954).  Pertussis continues to follow a cyclical pattern in Texas where increasing activity occurs over a 3-4 year period and then levels off sharply to begin another swell of 3-4 year cycle.  Using GIS mapping software, pertussis reports have shifted from being well-distributed in large metropolitan areas throughout the state to being highly concentrated in the north to northeastern section of the state in 2008.

Conclusions: Pertussis reports continue to increase in Texas.  Results of the analysis will be used to enhance further surveillance measures for pertussis.  Result data will also be utilized to assist with cocooning vaccination programs.  Next steps for Texas include further investigation into the shifting geographic distribution.