KEYWORD1:
Geographic Information Systems, Pertussis, Disease Surveillance, Vaccine Preventable Diseases

BACKGROUND:
A pertussis outbreak occurred in Yavapai County, Arizona, during the Fall of 2002. The outbreak was first reported in a middle school and spread to other schools and community sites over the course of several months. To obtain a more accurate visualization of the spread of pertussis over time, a geographic information system (GIS) was used to map and view cases of pertussis by time and outbreak site.

OBJECTIVE:
To demonstrate how GIS may be used to help visualize a pertussis outbreak.

METHOD:
Case and contact data were maintained in a Microsoft Access database created for the outbreak by the Yavapai County Health Department (YCHD) and the Arizona Department of Health Services (ADHS). YCHD and ADHS staff designed the GIS strategy, geocoded the database and mapped the data using ArcView.

RESULT:
Maps show the distribution of cases by school and residence over time. Relationships between epidemiologically linked cases and the index school reveal the magnitude and direction of spread from the index school as the outbreak progressed. Mapping identified the foci, physical and temporal relationships between cases, schools, and student residences.

CONCLUSION:
Because of the numbers of cases and school settings in this outbreak, GIS was helpful in characterizing the epidemiology of the outbreak.
LEARNINGOBJECTIVES:
Describe how GIS may be used to help understand and epidemiologically define an outbreak and visualize its spread.