Workpackage 6 Overview

Background

A description of the distribution of cases in time and space forms the basis of most epidemiological studies. To plot disease cases on a map has always been part of epidemiology, but recent advances in geographic information systems (GIS) allow this to be done much faster and to be more exploratory than before, which helps to identify associations that are not otherwise easily noticed. Further, more sophisticated tools for spatial statistical analyses have also been developed, offering new possibilities for epidemiological studies.

Within the field of the epidemiology of zoonotic diseases and food-borne infections, GIS may be used for basic surveillance and outbreak investigations. It can be very helpful to produce relevant maps promptly whereby clustering of cases can be observed. Not only cases, but also other components in the farm-to-fork continuum can be analysed by GIS, including the distribution of zoonotic agents or the animals that serve as their reservoirs, patterns of trade in live animals, routes for contaminated food products from one country to another, or demographic characteristics of human and animal populations. Advanced spatial–temporal analysis tools allow analysis of possible associations between different factors (e.g. an association between human disease and areas where a particular food item is consumed) and various types of cluster analyses can be made. Although the use of GIS within the epidemiology of food-borne infections is potentially a strong tool, GIS is not yet commonly applied.

Workpackage 6

WP6 was among the original first round of Med-Vet-Net Workpackages, but for a number of reasons the start was delayed. WP6 was reborn at the beginnning of 2006, with the main task of encouraging the use of GIS and building capacity among Workpackage members through teaching activities and through a number of small-scale scientific projects. The main project has been the construction of a web-based atlas of the spatial distribution of human salmonellosis in Europe during the past five to ten years (depending on data availability). This project was based on data from Enternet (the EU designated surveillance network on Salmonella) and the result is now publicly accessible at www.epigis.dk. The major challenge in this project has been to ‘translate’ the coded data reported to Enternet to something that can be linked to a spatial unit, such as a county or region, a process called geocoding. In fact, all administrative districts within the EU are officially assigned a code according to the ‘Nomenclature of Territorial Units for Statistics’ (NUTS), which should ideally be used by all reporting laboratories and authorities to ensure unique identification. To encourage the use of GIS among Workpackage members, a workshop was held where the competence of each participating institution was identified, and a short GIS training session was conducted. Following this, a training course in GIS in epidemiology open to all Med-Vet-Net scientists was organized and held in Copenhagen.

Current projects

Starting in early 2007, and new projects were added which are currently being worked on. One project concerns the spatial pattern of human VTEC cases related to the spatial location of cattle farms. This project will make use of simple spatial analysis such as buffer analysis, and basic spatial statistics like Moran’s I or Geary’s C depending on the data available in the different participating countries. Another project deals with spatial–temporal analyses of human salmonella data with the aim of illuminating trends in the distribution over time of different types of salmonella. A third project, the construction of a dynamic, interactive web atlas, is an extension of the previous Salmonella Atlas project. This project will, if successful, allow the web user to specify which data is displayed, so that for instance all serotypes, phage types and travel data can be shown. These maps will be ‘zoomable’.