Using GIS for Surveillance of Influenza-Like Illness in A School District

In the spring of 2009, as H1N1 and seasonal influenza surveillance activities increased, officials in Colorado's largest school district identified the need for more specific absenteeism data related to influenza-like illnesses in its schools, so that district administrators and public health officials could more accurately monitor and assess influenza activity at the community level, and make more informed decisions regarding school closures. The public school system implemented a surveillance system for the 2009-2010 school year, requiring each school to track and report daily absenteeism due to influenza-like illnesses. This data is sent to the Colorado Department of Public Health and Environment (CDPHE), where daily maps (.PDF and GEO .PDF format) using graduated symbols to quantify the number absent, or sent home, due to influenza like illness, and the rate of influenza-like illness per 100 students in each school are created using Geographic Information Systems (GIS) software (ArcGIS 9.3.1). The GIS software is used to model the volume, location, and time of influenza-like illness data. Jefferson County Public Health, in conjunction with the school district, utilizes the daily maps to visualize geographic trends in influenza-like illness occurrence, investigate aberrant absentee rates, and communicate information to school district and state health department officials, as well as the concerned public. The large number of students and schools in the district (the largest school district in Colorado with more than 84,000 students in 201 schools) make this surveillance data an excellent resource for epidemiologists and public health officials assessing the pandemic influenza in Colorado.