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September 28, 2005

ESSENCE: Protecting Public Health

Consider this scenario: Over the course of several days there is a spike in emergency room visits around the nation's capital and a steady rise in the number of people making appointments to see their family physician. At the same time, there's a run on cough medicines at suburban Washington drugstores, and more kids than usual are staying home from school.

This could simply be a nasty stretch during flu season—or the onset of a terrorist attack.

APL technology is at the forefront of a critical homeland defense effort to help public health officials assess a range of potentially dangerous situations and, if necessary, act quickly to protect citizens.

Health and homeland security representatives from the District of Columbia and surrounding counties in Maryland and Virginia worked with APL this year to launch the National Capital Area Disease Surveillance Network project, establishing a system for the early detection and notification of abnormal disease events that could cause widespread sickness and death.

Capitalizing on APL's innovative ESSENCE (Electronic Surveillance System for the Early Notification of Community-based Epidemics) technology, the network collects "health indicators" from a variety of sources, analyzes the data, and notifies users when statistical anomalies occur. The network is establishing independent surveillance nodes—operation centers—in the District, Maryland, and Virginia, with a central regional integration node at APL operated by Laboratory personnel to perform surveillance across jurisdictional boundaries. Operating 365 days a year, these centers will provide information to local public health departments.

Jurisdictions are looking at ways they can share these data, from which personal information has been removed, across their boundaries.

The project also aims to develop and implement protocols for a coordinated disease surveillance system, evaluate and improve network performance, and provide updates to the network based on APL's operational experience and ongoing disease surveillance research.

The network is being assembled from APL technology developed through collaboration with the Walter Reed Army Institute of Research. This collaboration implemented a worldwide military version of ESSENCE that has been operating since fall 2001.

Early Research

The Laboratory invested its own Independent Research and Development funds into the first version of the biosurveillance program, a collaborative project with the Maryland Emergency Management Agency and the Maryland Department of Health and Mental Hygiene.

APL engineers and computer scientists met with public health officials from across the state and elsewhere to identify data sources that could contain indicators of disease. The data had to have been collected for some other purpose—the suppliers were not to take on any additional burdens.

Security and privacy were also major factors; the recently enacted Health Insurance Portability Accountability Act required all information regarding the identity of the individuals be removed before the data could be sent and used for surveillance.

APL developed a prototype and demonstrated the system for state health officials. Not only could the system review collected data, but it also could apply an outbreak detection algorithm and view the data geographically to locate clusters of infection.

With the Maryland health department's endorsement, APL applied for demonstration-project grant under networkMaryland, an initiative to develop a statewide high-speed information network. APL also brought the concept to the Defense Advanced Research Projects Agency (DARPA) as a seedling project to obtain and effectively use health indicator data and perform surveillance during the celebrations leading up to and following the change of the millennium.

Building on Success

Working with health officials in Maryland's Howard and Anne Arundel counties, APL collected data on emergency room chief complaints, school absenteeism, and nursing home illness reports. The project also collected sales figures for over-the-counter flu and gastrointestinal medicines and tracked insurance claims across the state.

The APL team monitored an increase in flu-like illnesses that occurred early in January 2000 and, tapping into its expertise in signal processing, was able to subtract the larger illness from the background "noise" to detect smaller health events occurring at the same time. This led DARPA to initiate a program focused on the early detection of bioterrorist events.

The county health departments faced another major challenge: knowing the health status of military members and families. To address this issue, the seedling project acquired health-indicator data from Fort Meade for the winter flu season surrounding "Y2K." In early spring 2000, the project learned about a similar effort—called ESSENCE—focusing on the military population in the National Capital Area that the Walter Reed Army Institute for Research was running.

The two projects merged; APL and Walter Reed signed a collaborative research and development agreement and submitted joint proposal to DARPA, seeking funds to continue working on the technology and expanding it to both military and civilian public health authorities across the region.

Using the Data

ESSENCE is already proving to be a valuable tool. Officials in Montgomery County, Maryland, have used ESSENCE data to brief the county's Emergency Management Group during periods of national alert status, evaluate flu activity among county residents during the severe 2003–2004 flu season, and look for signs of illness associated with potential ricin exposure, SARS, or avian influenza.