FoodNet Geocoding to Address Disparities in Foodborne Illness

Project Name: FoodNet Geocoding to Address Disparities in Foodborne Illness

Project Status: Proposed

Point of Contact: Mary Patrick

Center: National Center for Emerging and Zoonotic Infectious Diseases

Keywords: FoodNet, geospatial, health disparities

Project Description: Foodborne disease is linked to social, geographic, and economic conditions, yet surveillance for foodborne disease in the United States provides little or no information about these factors. In this project, we will implement collection of small area geospatial information to enhance the effectiveness of surveillance for these infections in informing actions to reduce risk. This project will be conducted in the Foodborne Diseases Active Surveillance Network (FoodNet), a collaboration among CDC, 10 state health departments, the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA-FSIS), and the Food and Drug Administration (FDA).

Food safety is a CDC Winnable Battle and a major national priority, and FoodNet is the primary source of information for tracking foodborne disease for the nation. FoodNet conducts active, population-based surveillance for laboratory-confirmed infections caused by Campylobacter, Cryptosporidium, Cyclospora, Listeria, Salmonella, Shiga toxin–producing Escherichia coli (STEC) O157 and non-O157, Shigella, Vibrio, and Yersinia in 10 sites covering 15% of the U.S. population (48 million people in 2013). FoodNet monitors trends in the incidence of these infections over time. Although there have been some declines in incidence since FoodNet began in 1996, disease rates have remained relatively unchanged in recent years and work needs to be done to identify reasons for this lack of progress.

The incidence and severity of foodborne infections may be influenced by underlying determinants of health, such as income, education, employment, and social support systems. For many health conditions, individuals at the lower end of the socioeconomic status (SES) gradient experience poorer outcomes and reduced life expectancy compared with people who have more resources. Linking socioeconomic, geographic, and disease data can help us identify patterns in health disparities, guide future research studies, and ultimately develop public health interventions to reduce disease.

National and international authorities recommend that SES factors be collected routinely as part of all national surveillance systems. Census tracts (CTs) can serve as a proxy for individual-level SES data to understand the SES circumstances of communities as a way to gauge public health. CTs are permanent subdivisions of counties that generally have between 2,500 and 8,000 persons (~4,000 on average) and were designed by the US Census Bureau to be homogeneous with respect to neighborhood characteristics, economic status, and living conditions of persons residing within a relatively permanent statistical subdivision.

FoodNet has conducted a small pilot project to explore geocoding and been involved in the creation of an EIP geocoding protocol, but we do not routinely collect geographic information smaller than county-level. We propose to provide funds to our 10 FoodNet sites to facilitate geocoding to census tract of all 2010-2014 FoodNet cases. Geocoding will allow us to calculate incidence rates by census tract and directly link this information to US census data, enabling numerous types of analyses to address health disparities.

Project impact: This project would provide the most comprehensive source of data on foodborne infections at census tract level, spanning multiple years in 10 sites. Analysis could provide insight into health disparities, socioeconomic, and environmental factors associated with these infections, and how they differ by geographic region. Findings from this project can help to guide the development of future research studies.

Applicability of project for use by other public health programs: Methods developed from these analyses can be applied to other CDC programs interested in geospatial analysis. Geocoding this large volume of cases will help to test, evaluate, and refine geocoding protocols developed within the Emerging Infections Program (EIP) health disparities workgroup. c.

Methodology: Funds will be provided to the 10 FoodNet sites to support personnel training, time, and/or computer software needed to facilitate geocoding of cases. Using methods outlined in the EIP geocoding protocol, personnel at the site will geocode case address information to identify the corresponding census tract. The staff will then remove the address, latitude, and longitude, but retain FoodNet ID fields (i.e., state, PersonID, PatID). The census tract and ID fields will be sent to CDC through a secure FTP site. At CDC, census tract will be linked to routine surveillance data as well as the most currently available census data.

For more information about this project, please contact the CHIIC at or Brian Lee at

Page last reviewed: February 15, 2019