County A was mapped by driving all roads. The latitude and longitude of all suspected swine facilities were recorded using a portable GPS navigation system. While this method of surveillance identified many swine facilities, several challenges were encountered. Minimally maintained roads were difficult to traverse, the topography of the land often limited the line of site, the method consumed a great amount of time, and there were potential biosecurity concerns to driving near multiple sites.
To overcome these challenges, alternate methods including computer mapping and aerial surveillance methods were evaluated. Computer mapping capabilities were limited due to outdated satellite imagery. In addition, animal facilities’ utility could not be identified. Aerial mapping appeared promising and a protocol was developed and executed for Counties A, B, and C. Known swine facilities were plotted in advance to use as landmarks. In the air, the portable GPS unit proved useful to accurately locate previously unknown swine facilities. Confinement facilities were easily identified and plotted from the air.
Results and discussion
An analysis was performed to compare the efficiency of aerial mapping to surveying a county by road. County A was evaluated by both driving and flying. The number of facilities identified by driving and flying were 33 and 35, respectively. County A required 3.05min/km2 at a cost $1.21/km2 while driving. Aerial mapping of Counties A, B and C required 0.15min/km2 and resulted in a cost of $0.39/km.2 Aerial mapping increased time efficiencies by 95% while decreasing cost by 31% of the cost as driving.
Aerial mapping of a county to identify swine facilities proved to be more time efficient and cost effective than mapping by driving.
B. Miller, C. Dorazio, B. Payne. Aerial mapping: Adding to the swine industry’s toolbox for area regional disease control. AASV 2010: 327.