Propagation of program control: a tool for distributed disease surveillance.

PURPOSE: The purpose of the study was (1) to identify the requirements for syndromic, disease surveillance and epidemiology systems arising from events such as the SARS outbreak in March 2003, and the deliberate spread of Bacillus anthracis, or anthrax, in the US in 2001; and (2) to use these specifications as input to the construction of a system intended to meet these requirements. An important goal was to provide information about the diffusion of a communicable disease without being dependent on centralised storage of information about individual patients or revealing patient-identifiable information.

METHODS: The method applied is rooted in the engineering paradigm involving phases of analysis, system specification, design, implementation, and testing. The requirements were established from earlier projects' conclusions and analysis of disease outbreaks. The requirements were validated by a literature study of syndromic and disease surveillance systems. The system was tested on simulated EHR databases generated from microbiology laboratory data.

RESULTS: A requirements list that a syndromic and disease surveillance system should meet, and an open source system, "The Snow Agent system", has been developed. The Snow Agent system is a distributed system for monitoring the status of a population's health by distributing processes to, and extracting epidemiological data directly from, the electronic health records (EHR) system in a geographic area.

CONCLUSIONS: Syndromic and disease surveillance tools should be able to operate at all levels in the health systems and across national borders. Such systems should avoid transferring patient identifiable data, support two-way communications and be able to define and incorporate new and unknown diseases and syndrome definitions that should be reported by the system. The initial tests of the Snow Agent system shows that it will easily scale to national level in Norway.