The development and validation of a geographic information system database for the poultry industry on the Delmarva Peninsula

A geographic information system (GIS) database of the poultry industry on the Delmarva Peninsula was developed through a cooperative agreement between the Delmarva Poultry Industry, Inc., and the Virginia-Maryland Regional College of Veterinary Medicine. The purpose of this database was to facilitate disease surveillance and assist in managing the response to outbreaks and other emergencies. Two methods of data collection were employed and are described in this paper. The first method was to visit each poultry farm and collect the latitude and longitude coordinates with a handheld global positioning system unit. The second method used property ownership information, aerial photographs, and a GIS to determine the latitude and longitude of each poultry farm. There was no significant difference between the two methods in the accuracy of the results, but there was a large difference in the amount of time and money necessary to obtain the data. These findings indicate that whereas there are many ways to obtain accurate data for a GIS database, other factors may influence which method is chosen. A subset of farms contained within the database was visited to assess the accuracy of the locations contained within the database. Of the 240 farms visited for validation, 212 showed evidence of a functioning or previously functioning poultry operation. The corresponding error rate was 11%. This demonstrates the need to assure that the database is kept up to date to ensure that attrition among poultry growers is recorded. Several potential factors that might contribute to sources of error are discussed.