"The Network" Newsletter, Part 1: A Case for Distributed Flu Surveillance

A Case for Distributed Flu Surveillance: The International Society for Disease Surveillance (ISDS) Distributed Surveillance Taskforce for Real-time Influenza Burden Tracking and Evaluation (DiSTRIBuTE)

by Don Olson

This article is a part of a series that will be published in the Global Outreach newsletter, "The Network." A pdf version of "The Network" is coming soon!

The DiSTRIBuTE project was proof of concept effort initiated in October 2006 at the Annual ISDS Conference in Baltimore. It was developed as an approach to influenza morbidity surveillance based on existing state and local electronic syndromic surveillance capabilities and expertise. The projects design, implementation and evolution has involved ongoing collaboration with local, state and national health departments and a multidisciplinary team representing the ISDS membership. Supported by the Markle Foundation and the US Centers for Disease Control and Prevention (CDC), through a cooperative agreement with the National Association of County and City Health Officials (NACCHO), the ISDS DiSTRIBuTE Project has established a model for international distributed influenza surveillance by building on existing national, state and local programs.

The project enrolls volunteer health departments that conduct electronic syndrome-based surveillance from emergency department or outpatient settings. The participant agencies report electronically summarized daily counts of illness and total visits by broad age group (<2, 2-4, 5-17, 18-44, 45-64, 65+ yrs) and geographic area (as US 3-digit zip code, or larger region) to a secure internet site. Weekly aggregate ratios of febrile, respiratory and influenza-like syndromes, based on each region’s routine syndromic criteria for seasonal influenza, to total visits, are visualized as regional time-series and age-specific temporal epidemic response surface plots (see Figure).

Created with a distributed architecture, the DiSTRIBuTE project requires that all individual-level data remain local, and only broad aggregate counts by reported out. While many electronic syndromic surveillance efforts have focused on central collection in huge individual level databases, the DiSTRIBuTE project asks for data based on the question What summarized level of data are epidemiologically needed? And as the limitations of this model are reached, the project is investigating how standardization of syndromes, generalizability of the model, ad hoc investigation and system evaluation can be conducted through reverse queries, where the questions are asked of the participating sites, the data are reaggregated locally and the new summarized counts are shared.

The DiSTRIBuTE project’s approach is based on distributed data collection and analysis with central monitoring of summary information. For influenza-related morbidity, limiting the data request to the information that is truly the minimum required (summarized counts), the system has retained the ability to demonstrate robust monitoring, quickly and cost effectively. The very low risk of privacy breach has encouraged trust among data sources and has facilitated voluntary participation at both the national and international levels.

For more information, or if your city, county, state or national surveillance system is interested in joining the project, please contact Don Olson at distribute@syndromic.org




Figure: Draft visualizations by US jurisdiction, 2006-2009: fever, respiratory, influenza-like syndrome time-series as ratios, with national US CDC sentinel and viral influenza isolate data (top); and age-specific temporal epidemic response surface (TERS) plots (bottom).